Volkswagen Workshop Service and Repair Manuals

Display group 6 -Altitude adaption-

Read measured value block 6

⇒

[ltrif ] Indicated on display

xxxx rpm

xxx mg/H

xx.x <°

x.x

1

2

3

4

[ltrif ] Display zones

Specification

Evaluation

Altitude correction factor

0.9...1.1

---

Throttle valve angle

1.9...5.7 <°

Air mass drawn in (engine load)

76...164 mg/H

=> Page 01-72

Engine speed (idling speed)

760...880 rpm

=> Page 01-69

Display group 7 -Idling adjustment-

Read measured value block 7

⇒

[ltrif ] Indicated on display

xx.x <°

x.xx

x.xx

xxxx

1

2

3

4

[ltrif ] Display zones

Specification

Evaluation

Engine operating condition

0100

---

Idling control learnt value (automatic gearbox with gear selected)

0.95...1.05

---

Idling control learnt value (manual gearbox in neutral/automatic gearbox selector lever in P or N)

0.95...1.05

---

Throttle valve angle

1.9...5.7 <°

=> Page 01-74

Significance when display = 1

x

x

x

x

Operating status of engine

1

Overrun

1

Idling

1

Part throttle

1

Full throttle

Display group 8 -Idling stabilisation-

Read measured value block 8

⇒

[ltrif ] Indicated on display

xxxx rpm

xxxx rpm

xx %

x.x g/s

1

2

3

4

[ltrif ] Display zones

Specification

Evaluation

Amount of air drawn in

1.0...3.2 g/s

---

Idling control

-10...15 %

---

Engine speed (idling speed) -specification-

800...840 rpm

---

Engine speed (idling speed)

760...880 rpm

=> Page 01-69

Display group 9 -Idling air requirements-

Read measured value block 9

⇒

[ltrif ] Indicated on display

xx %

xxxxxxxx

xxx °C

xxxx rpm

1

2

3

4

[ltrif ] Display zones

Specification

Evaluation

Engine speed

760...880 rpm

---

Coolant temperature

80...110 °C

=> Page 01-70

Throttle valve control part operating status

00000000

---

Idling control

-10...15 %

---

x

x

x

x

x

x

x

x

Significance when display = 1

0

Not allocated

0

Not allocated

0

Not allocated

0

Not allocated

1

Fault has occurred during the adaption of the throttle valve (interrogate fault memory
=> Page 01-9 )

1

No current supply to throttle valve control part (duty cycle = 0)

1

Adaption interrupted due to the battery voltage being too low (below 8V).

1

Idling switch open (interrogation of switch)

Display group 10 -Lambda control and activated charcoal filter system-

Read measured value block 10

⇒

[ltrif ] Indicated on display

xx %

x.xx V

xx %

xx %

1

2

3

4

[ltrif ] Display zones

Specification

Evaluation

Lambda correction factor when tank venting is active

-20...2 %

---

Activated charcoal filter solenoid valve 1 duty cycle

0...20 %

---

Lambda probe voltage

0.00...1.00 V

=> Page 01-86

Lambda regulator

-25...25 %

---

V.A.G 1551 display

Possible fault cause

Fault elimination

Display does not fluctuate

- Large amount of unmetered air

- Check air intake system for leaks

(Constant 0.00...
0.30 V

- Spark plug defective

- Check spark plugs

or

- Fuel pressure too low or too high

- Check fuel pressure regulator and holding pressure => Page 24-69

Constant 0.70...
1.00 V)

- Injector defective

- Check injectors => Page 24-62

- Coolant temperature sender defective

- Check coolant temperature sender

- Activated charcoal filter solenoid valve 1

- Check solenoid valve 1 for activated charcoal filter => Page 01-57 , final control diagnosis

- Lambda probe heating not functioning

- Check Lambda probe heating
=> Page 24-26

Continued on next page

- Lambda probe defective or soiled

- Check Lambda probe => Page 24-79

V.A.G 1551 display

Possible fault cause

Fault elimination

Constant approx. 5 V

- Short to positive via:
- Lambda probe, probe wiring, earth wiring, engine control unit

- Check Lambda probe wiring
=> Page 24-86

Constant between
1.50...1.60 V

- Wiring open circuit via:
- Fuse, Lambda probe, probe wire, earth wire, engine control unit

Constant 0.00 V

- Short to earth via:
- Lambda probe, probe wire, earth wire, engine control unit

Display group 11 -Lambda learning values-

Read measured value block 11

⇒

[ltrif ] Indicated on display

x.xx ms

x.xx ms

x.xx

xxxxxxxx

1

2

3

4

[ltrif ] Display zones

Specification

Evaluation

Condition of tank breather valve

---

---

Lambda learnt value at part load

0.9...1.15

=> Page 01-88

Lambda learnt value at idling

-0.1...1.0 ms

=> Page 01-88

Injection period

2.00...4.10 ms

=> Page 01-75

V.A.G 1551 display

Possible fault cause

Fault elimination

Outside tolerance range

- Minus range: Mixture too rich, Lambda control weakens mixture
- Positive range: Mixture too lean, Lambda control enriches mixture

- Wait 30 seconds until the display has stabilised

- Unmetered air

- Check intake system for leaks
=> Page 24-73

- Injector defective

- Check injection rate => Page 24-62

x

x

x

x

x

x

x

x

Significance when display = 1

0

Vacant

1

Transition to vapour content check via fuel tank breather valve

1

Transition to fuel tank breather valve minimum operating level

1

Transition to fuel tank breather valve closure

1

Vapour content check via fuel tank breather valve

1

Fuel tank breather valve operating normally

1

Fuel tank breather valve minimum operating level

1

Fuel tank breather valve closed

Display group 12 -Lambda control-

Read measured value block 12

⇒

[ltrif ] Indicated on display

xxxx rpm

xxx mg/H

xx %

x.xx V

1

2

3

4

[ltrif ] Display zones

Specification

Evaluation

Lambda probe voltage

0.00...1.00 V

=> Page 01-86

Lambda regulation

-25...25 %

---

Air mass drawn in (engine load)

76...164 mg/H

=> Page 01-72

Engine speed (idling speed)

760...880 rpm

=> Page 01-69

Display group 13 -Fuel consumption-

Read measured value block 13

⇒

[ltrif ] Indicated on display

xxxx rpm

xxx mg/H

xxx km/h

x.xx l/h

1

2

3

4

[ltrif ] Display zones

Specification

Evaluation

Fuel consumption

0.50...2.00 l/h

---

Road speed

0 km/h

---

Air mass drawn in (engine load)

76...164 mg/H

=> Page 01-72

Engine speed (idling speed)

760...880 rpm

=> Page 01-69