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Motronic self-diagnosis
Fault codes 01252 - 18020
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V.A.G 1551 printout
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Possible causes of fault
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Possible
effects
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Fault remedy
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01252
Injector, cylinder 4 -N33
*Short to ground
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- Short to ground in control wire from injector to Motronic control unit -J220
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- Engine idles roughly or cuts out
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- Test fuse -S34
- Check injectors
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*Short to positive
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- Short to positive in control wire from injector to Motronic control unit -J220
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* Output open
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- Open circuit in control wire from injector to Motronic control unit -J220
- Fuse -S34 defective
- Open circuit between injector and fuse -S34 (voltage supply)
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*) One of these fault types appears in addition to the affected component.
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V.A.G 1551 printout
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Possible causes of fault
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Possible
effects
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Fault remedy
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01259
Fuel pump relay -J17
* Open circuit/short circuit to ground
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- Short to ground or open circuit between fuel pump relay and Motronic control unit -J220
- Fuel pump relay defective
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- For open circuit: Engine will not run
- For short to ground: Engine runs normally, but there is a higher current consumption when the ignition is on, as the relay is permanently actuated and the fuel pump runs constantly, even though the engine is not running
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- Test fuel pump relay
=> Page 24-31
- Rectify open circuit or short circuit according to the current flow diagram
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*Short to positive
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- Short to positive between fuel pump relay and Motronic control unit -J220
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- Engine will not run
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*) One of these fault types appears in addition to the affected component.
Engine code AEB only:
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V.A.G 1551 printout
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Possible causes of fault
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Possible
effects
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Fault remedy
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01262
Boost pressure control solenoid valve
-N75
*Short to ground
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- Short to ground between boost pressure control solenoid valve -N75 and Motronic control unit -J220
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- Increased boost pressure (fault 00544 is set as a follow-on fault)
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- Check fuse -S29
- Test boost pressure control solenoid valve
=> Page 24-54
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*Short to positive
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- Short to positive between boost pressure control solenoid valve -N75 and Motronic control unit -J220
- Open circuit between boost pressure control solenoid valve -N75 and Motronic control unit -J220
- Fuse -S29 defective
- Open circuit between solenoid valve and fuse -S29 (voltage supply)
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- Boost pressure too low
- Loss of power
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*) One of these fault types appears in addition to the affected component.
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V.A.G 1551 printout
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Possible causes of fault
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Possible
effects
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Fault remedy
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16486
Air mass meter signal too small
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- Open circuit between air mass meter and -J220
- Short to positive or ground in signal wire to -J220
- Air mass meter defective
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- Emergency running mode (substitute value from throttle valve angle and engine speed), thus no noticeable effect on engine running
- Restriction of boost pressure (AEB engine only)
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- Rectify short or open circuit according to the
current flow diagram
- Test air mass meter
- Read measured value block,- Display group 02
=>Page
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16487
Air mass meter signal too large
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- Signal input in control unit defective (-J220 defective)
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16496
Intake air temperature Signal too low
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- Open circuit between intake air temperature sender -G42 and -J220
- Short to positive or ground in signal wire to -J220
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- Emergency running mode (substitute value: fixed + 20 oC)
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- Rectify short or open circuit according to the current flow diagram
- Test intake air temperature sender - =>Page01-71
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16497
Intake air temperature Signal too high
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- Intake air temperature sender -G42 defective
- Signal input in control unit defective (-J220 defective)
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Note on fault codes 16496 and 16497 (engine code AEB only):
As soon as one of the two faults relating to intake temperature is detected the control unit assumes a fixed substitute value of 20oC. This substitute value is not displayed in the `Read measured value block' function.
In the event of an open circuit in the wiring or the sender the value -46.5oC is displayed.
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V.A.G 1551 printout
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Possible causes of fault
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Possible effects
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Fault remedy
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16500
Coolant temperature plausibility
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- Open circuit between intake air temperature sender -G62 and -J220
- Short to ground or positive in wiring connection between temperature sender and -J220
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- Engine running problems when warm
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- Check coolant temperature sender -
- Rectify short or open circuit according to the
current flow diagram
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16501
Coolant temperature Signal too low
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- Contact resistances at plug connections of sender or control unit
- Coolant temperature sender -G62 defective
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16502
Coolant temperature Signal too high
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- Moisture in temperature sender connector
- Signal input in control unit defective (-J220 defective)
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Note on Fault code 16500:
The temperature curve in the range up from 20 oC to 60oC is compared to a model curve stored in the control unit. The rate of rise of the model curve is slower than the actual value. If the actual values become too slow on account of a fault, they will eventually coincide with the model values. This is not plausible.
Note on fault codes 16500, 16501 and 16502:
As soon as one of the faults is identified, the control unit uses first of all a substitute value formed from the model curve stored in the control unit. After a certain time a fixed substitute value is assumed for an engine at operating temperature. ADP engine 75 oC, ADR and AEB engine 60 oC.
In the event of a fault the substitute value is displayed in the Measured value block, Display group 03.
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V.A.G 1551 printout
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Possible causes of fault
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Possible effects
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Fault remedy
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16505
Plausibility of throttle valve potentiometer
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- Moisture or corrosion
- in plug connection at potentiometer
- Potentiometer defective
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- Slight misfiring under acceleration
- Idling speed control behaviour unstable
- Load change jolt on accelerator release
- Restriction of boost pressure (AEB engine only)
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- Check throttle valve control part
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16506
Throttle valve potentiometer: signal too small
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- Short to ground in potentiometer or in wiring connection between potentiometer and -J220
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- Slight misfiring under acceleration
- Load change jolt on accelerator release
- Restriction of boost pressure (AEB engine only)
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- Rectify short circuit according to current flow diagram
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16507
Throttle valve potentiometer: signal too large
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- Open circuit or short to positive in potentiometer or in wiring connection between potentiometer and -J220
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- Slight misfiring under acceleration
- Load change jolt on accelerator release
- Restriction of boost pressure (AEB engine only)
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- Eliminate open circuit.
or short circuit according
to the current flow diagram
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Note on Fault code 16505:
The air throughput (air mass) at the relevant speed is compared with the throttle angle.
Note on fault codes 16505, 16506 and 16507:
- As soon as one of the faults is detected the control unit uses a substitute value formed from the engine speed.
- If a fault occurs simultaneously on the throttle valve potentiometer and the air mass meter then the emergency running mode is not available - the engine stalls.
- On AEB engines full-load detection is not possible - excessively high exhaust gas temperature at high loads and high engine speeds (risk
of turbocharger overload).
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V.A.G 1551 printout
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Possible causes of fault
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Possible effects
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Fault remedy
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16514
B1-S1 malfunction
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- Short between lambda probe signal wire and reference ground
- Amplitude of signal voltage too small
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- Emissions not OK
- Increased fuel consumption
- Soot on spark plugs
- Lambda control switches to open loop control
- Instable idling
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- Rectify open circuit or short circuit according to the current flow diagram
- Check lambda control
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16515
B1-S1 voltage too small
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- Lambda probe defective (dirty)
- Short to ground or short to screening in signal wire
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16516
B1-S1 voltage too large
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- Lambda probe defective (dirty)
- Short to positive in signal wire
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16518
B1-S1 no activity
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- Lambda probe defective (dirty)
- Open circuit in wiring to control unit
- No probe heating function
- Fuse -S29 defective
- Wiring connection for probe heating defective
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V.A.G 1551 printout
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Possible causes of fault
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Possible effects
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Fault remedy
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16705
Engine speed sender
Plausibility
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- Metal swarf on sensor
- Distance between sender and sender wheel greater than 1.3 mm
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- Engine misfiring
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- Check engine speed sender - => Page 28-27
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16706
Engine speed sender
No signal
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- Open circuit at sender
- Open circuit between -J220 and sender
- Short to ground or short to screening in signal wire
- Open circuit in screening of sender
- Sender defective
- Signal input in control unit defective (-J220 defective)
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- Engine will not start
- Engine cuts out
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- Rectify short or open circuit according to the
current flow diagram
- Check engine speed
sender - => Page 28-27
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Note:
The plausibility fault is set if the number of signals per crankshaft revolution from the reference gap is incorrect (60 signals).
- Additional signals can be created due to swarf.
- Damaged teeth, an excessive gap between sender and sender wheel or a bent sender wheel can cause signals to be missing or too small, resulting in non-detection.
- The signal sequence can be irregular if the sender wheel is loose.
- Additional signals can be created due to interference signals.
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V.A.G 1551 printout
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Possible causes of fault
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Possible effects
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Fault remedy
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16711
Knock sensor 1, signal too small
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- Knock sensor loose or corrosion on connector
- Open circuit or short between knock sensor and -J220
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- - High fuel consumption
- Loss of power
- Restriction of boost pressure (ADR and AEB engines only)
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- Read measured value block, Display group 16
- Tightening torque of
knock sensor: 20 Nm
- Rectify short or open circuit according to the
current flow diagram
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16716
Knock sensor 2, signal too small
ADR and AEB engines only
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- Short circuit between knock sensor and ground or to screening
- Knock sensor defective
- Signal input in control unit defective (-J220 defective)
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V.A.G 1551 printout
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Possible causes of fault
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Possible effects
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Fault remedy
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16885
Vehicle speed signal
Plausibility
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- Vehicle speed sender -G68 defective
- Short or open circuit between -G68 and speedometer -G21
- Speedometer -G21 defective
- Short in signal wire between speedometer and another control unit which is using the vehicle speed signal
- Short or open circuit between dash panel insert and Motronic control unit -J220
- Signal input in Motronic control unit defective (-J220 defective)
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- No A/C compressor shut-off in first gear under full throttle
- Brief deviation between idling speed and specified speed
- Malfunctioning of systems which use the vehicle speed signal
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- Check vehicle speed signal
=> Current Flow Diagrams, Electrical Fault-Finding and Fitting Locations
- Read measured value block, Display group 01 - => Page 01-65
- Check vehicle speed signal
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16989
Control unit defective
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- Control unit malfunction in overrun at 1320....3000 rpm,
- time 2 s
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- Loss of power
- Restriction of boost pressure (AEB engine only)
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- Replace control unit
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V.A.G 1551 printout
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Possible causes of fault
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Possible effects
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Fault remedy
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17733
Knock control cyl.1: control limit reached
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- Poor quality fuel (less than RON 91)
- Intake air temperature sender faulty (AEB engine only)
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- High fuel consumption
- Loss of power
- Irregular engine running
- Maximum speed is not reached
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- Fill up with petrol of at least 91 RON
- Check intake air temperature sender
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17734
Knock control cyl.2: control limit reached
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- Abnormal engine running noise (ancillaries loose)
- Open circuit in screening of knock sensor 1 or 2
- Loose contact in wiring harness
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- Check knock sensors
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17735
Knock control cyl.3: control limit reached
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- Loose contact in wiring harness
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17736
Knock control cyl.4: control limit reached
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V.A.G 1551 printout
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Possible causes of fault
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Possible effects
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Fault remedy
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17913
Idling switch not closing/open circuit
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- Throttle valve sticking
- Floor mat pressing down on accelerator pedal
- Throttle cable setting
- Open circuit between idling switch and -J220
- Signal input in control unit defective (-J220 defective)
- Idling switch defective
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- Idling speed outside specified range
- Load change jolt on accelerator release
- Air conditioner compressor does not cut in until about 2000 rpm
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- Check throttle valve control part => Page 24-58
- Adjust throttle cable
- Rectify open circuit
according to the current flow diagram
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17914
Idling switch not opening/short to ground
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- Short to ground between idling switch and -J220
- Moisture in throttle valve connector
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- Idling speed control switches to open loop control
- Idling speed outside specified range
- Load change jolt on accelerator release
- Air conditioner compressor does not cut in until about 2000 rpm
- At coolant temperature below 40 oC overrun shut-off at approx. 1500 rpm before fault is stored
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- Check throttle valve control part => Page 24-58
- Adjust throttle cable
- Rectify short circuit according to - current flow diagram
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V.A.G 1551 printout
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Possible causes of fault
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Possible effects
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Fault remedy
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17978
Engine control unit
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- Test wiring of immobiliser
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blocked
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- Wiring connection or short circuit to ground or positive between immobiliser control unit and engine control unit
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- Engine starts briefly and cuts out again after approx. 1 second
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=> Current flow diagrams, Electrical fault-finding and fitting locations binder, Immobiliser fault-finding program
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- Attempt made to start vehicle with unauthorised key
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- Check and if necessary perform key adaptation
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- Engine control unit replaced but not adapted to immobiliser
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- Perform adaptation of engine control unit
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V.A.G 1551 printout
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Possible causes of fault
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Possible effects
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Fault remedy
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18010
Voltage supply term. 30, undervoltage detected
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- Battery disconnected
- Permanent power supply for control unit was disconnected (connector D)
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______________
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- Check power supply for
Motronic control unit
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18020
Engine control unit incorrectly encoded
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- Control unit detects signals from automatic gearbox even though engine control unit is encoded for manual gearbox
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- No noticeable effects
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- Encode control unit with
correct code
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