DTC P2261 - LLU
Diagnostic Instructions
DTC Descriptor
DTC P2261 00: Turbocharger Bypass Valve
Stuck
Circuit/System Description
The turbocharger incorporates a wastegate that is controlled by
a pressure differential, that is determined by the engine control
module (ECM) by means of a pulse width modulation (PWM) solenoid,
in order to regulate the pressure ratio of the compressor. A charge
air bypass valve is integrated within the module, and is also
controlled by the ECM by utilising a remotely mounted solenoid to
prevent compressor surging and damage from vibrations by opening
during abrupt closed throttle conditions. When the valve is
commanded open during closed throttle deceleration conditions, the
bypass valve allows the air to recirculate in the turbocharger and
maintain compressor speed. Within a calibrated range during the
closed throttle event, or upon a wide open throttle command, the
valve will then close to optimise turbocharger response.
Front wheel drive platforms also incorporate a charge air bypass
valve vacuum tank. The purpose of the tank is to provide an instant
source of vacuum to the bypass valve, when it is commanded open by
the ECM. This results in less pressure buildup under closed
throttle conditions, thereby reducing compressor noise and
surge.
The purpose of this diagnostic is to determine if the charge air
bypass valve is stuck closed. The ECM will first verify the
integrity of the following sensors. The ECM then compares the
actual measured mass air flow (MAF) to a modelled airflow that is
derived from these inputs:
Conditions for Running the DTC
• |
DTCs P0033 00, P0034 00, P0035 00,
P0097 00, P0098 00, P0100 00, P0101 00,
P0102 00, P0103 00, P0121 00, P0122 00,
P0123 00, P0221 00, P0222 00, P0223 00,
P0234 00, P0237 00, P0238 00, P0299 00,
P2228 00, or P2229 00 are not set. |
• |
The boost pressure versus the barometric pressure
(BARO) ratio is between 1.1-3.3. |
• |
The charge air bypass valve has been commanded ON
for greater than 1 s immediately after an abrupt closed
throttle has occurred and the resulting pressure ratio across the
compressor exceeds the calibrated pressure ratio limit. |
• |
The battery voltage is between 10-18 V. |
• |
The engine coolant temperature is above
39°C (102°F). |
• |
The intake air temperature is above
4.5°C (40°F). |
• |
This DTC runs continuously within the enabling
conditions. |
Conditions for Setting the DTC
The ECM by comparing the measured MAF to the modelled MAF has
detected a series of pulsations in the induction system that exceed
a calibrated threshold.
Action Taken When the DTC Sets
• |
DTC P2261 00 is a Type C DTC. |
• |
The service vehicle soon indicator will
illuminate. |
Conditions for Clearing the DTC
DTC P2261 00 is a Type C DTC.
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Verify that DTCs P0033 00, P0034 00, or
P0035 00 are not set.
- Use the scan tool output controls to command the
Turbocharger Bypass Solenoid to 100% and down to 0%. An audible
click should be heard and felt.
- Set up the scan tool for a snapshot of the induction
data list. With the handbrake on, the vehicle transmission in
neutral, and the engine idling, perform a wide open throttle and
then quickly release the accelerator. Review the Boost Pressure
Sensor parameter. There should not be any abnormal pulsations of
the parameter.
- Operate the vehicle within the conditions for running
the DTC to verify the DTC does not reset. You may also operate the
vehicle within the conditions that you observed from the freeze
frame/failure records data.
Circuit/System Testing
- Inspect for any vacuum leaks, damage, restrictions,
improper routing or connecting of the vacuum hoses on the
Q40 Turbocharger Bypass Solenoid Valve solenoid and the charge
air bypass valve vacuum tank.
- Clear the DTC and operate the vehicle within the
conditions for running the DTC.
⇒ |
If the DTC cannot be cleared or continues to
reset, then replace the charge air bypass valve. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic
procedure.
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