Diagnostics and check Turbocharger (Discovery 3)

Inspection and verification

CAUTION: The following checks may require you to work close to hot parts. Wear appropriate protective equipment. Failure to follow this instruction may result in personal injury.

CAUTION: The turbocharger may continue to rotate after the engine has stopped. Do not attempt to test the turbocharger until at least one minute has passed since the engine was turned off. Failure to follow this instruction may result in personal injury.

1. Accurately identify the problem indicated by the customer.

2. Visually inspect for obvious mechanical and electrical problems.

Mechanical elements	Electrical elements
Air intake system Hose (And) /hose connections Turbocharger General condition of the engine.	Electrical circuit (And) Turbocharger drive Engine control module (ECM) Electrical connectors and wiring harnesses

3. If an obvious cause for a customer-specified or customer-reported issue is identified, correct the issue before proceeding to the next step (if possible).

4. Read all DTCs before referring to the symptom table or DTC index (DTC) using an approved diagnostic system or scan tool.

Clear all DTCs after troubleshooting.

Symptom table

Symptom	Possible reason	Action taken
Poor dynamic performance	Low/contaminated fuel Clogged air intake system General condition of the engine ECM malfunction	Check the level and condition of the fuel. Check the air intake system for blockage. Check engine condition, compression, etc. Check for DTCs If an ECM malfunction is suspected, refer to the Warranty Policy and Procedures Manual.
No boost	Electrical connectors and wiring harnesses Clogged air intake system Charge air cooler clogged/leaking Turbocharger Drive Malfunction Turbocharger failure ECM malfunction	Check electrical connectors and wiring harnesses. Check air intake system for blockage/leakage (see "Visual check"). For testing the air intake system. Check turbocharger actuator and electrical circuits. Refer to electrical manuals. Check the mechanical condition of the turbocharger. If an ECM malfunction is suspected, refer to the Warranty Policy and Procedures Manual.
No boost/excessive noise	Turbocharger failure	Disconnect the intake and exhaust piping and manually turn the turbocharger shaft. Any difficulty in smooth scrolling indicates a malfunction. Check the turbocharger shaft for any lateral movement. Excessive movement indicates a malfunction. If in doubt, compare the suspect block with the new turbocharger block.

DTC pointer

NOTE: Universal Scan Tools may not read the listed codes or may only read 5-digit codes. Match the 5 digits from the scan tool with the first 5 digits of the listed 7 digit code to identify the problem (the last 2 digits give additional information read by the approved diagnostic system).

NOTE: See section 303-14 for a complete list of powertrain DTCs "Electronic engine management system" in the workshop manual.

DTC	State	Possible reasons	Action taken
P004500	Turbocharger / mechanical compressor boost sensor A circuit - open circuit	Variable Geometry Turbocharger Actuator Circuit (VGT): high resistance VGT Actuator Circuit Short to Ground Malfunction of the VGT actuator ECM malfunction	Refer to the electrical manual and check the VGT electrical circuit. If there is any doubt about the functionality of the module, refer to the Warranty Policy and Procedures Manual.
P004600	Turbocharger/Mechanical Compressor Control Circuit A Range/Performance Problems	Variable Geometry Turbocharger Actuator Circuit (VGT): high resistance VGT Actuator Circuit Short to Ground VGT Actuator Circuit Short to + Battery VGT drive failure ECM malfunction	Refer to the electrical manual and check the VGT electrical circuit. If there is any doubt about the functionality of the module, refer to the Warranty Policy and Procedures Manual.
P004700	Turbocharger/Mechanical Compressor Boost Sensor A Circuit Low Voltage	Variable Geometry Turbocharger Actuator Circuit (VGT): high resistance VGT Actuator Circuit Short to Ground VGT drive failure ECM malfunction	Refer to the electrical manual and check the VGT electrical circuit. If there is any doubt about the functionality of the module, refer to the Warranty Policy and Procedures Manual.
P004800	Turbocharger/Mechanical Compressor Boost Sensor A Circuit High Voltage	VGT Actuator Circuit Short to + Battery VGT drive failure ECM malfunction	Refer to the electrical manual and check the VGT electrical circuit. If there is any doubt about the functionality of the module, refer to the Warranty Policy and Procedures Manual.
P023400	Turbocharger/Mechanical Compressor Boost Overpressure A	Air leakage Manifold Absolute Pressure Sensor Circuit High Resistance (MAP) MAP sensor circuit short circuit to ground MAP sensor circuit short circuit to + battery MAP sensor malfunction Exhaust Gas Recirculation System Malfunction (EGR) Malfunction of the VGT actuator	Refer to the relevant section in the workshop manual. Check the MAP sensor and circuits. Refer to electrical manuals. EGR valve checks are described in the appropriate section of the workshop manual. Check for DTCs indicating a problem with the EGR or VGT actuator. If there is any doubt about the functionality of the module, refer to the Warranty Policy and Procedures Manual.
P029900	Reduced boost pressure turbocharger / mechanical compressor A	Air leak after turbocharger MAP sensor circuit high resistance MAP sensor circuit short circuit to ground MAP sensor circuit short circuit to + battery MAP sensor malfunction Exhaust Gas Recirculation System Malfunction (EGR) Fault VGT ECM malfunction	Refer to the relevant section in the workshop manual. Check the MAP sensor and circuits. Refer to electrical manuals. EGR valve checks are described in the appropriate section of the workshop manual. Check for DTCs indicating a problem with the EGR or VGT actuator. If there is any doubt about the functionality of the module, refer to the Warranty Policy and Procedures Manual.
P226300	Turbocharger/Compressor Boost System - Operating Parameters	Air leak after turbocharger Intake air temperature sensor circuit (IAT): high resistance, short circuit to ground, short circuit to power Manifold Absolute Pressure Sensor Circuit (IDA): high resistance, short circuit to ground, short circuit to battery + Mass Air Flow Sensor Circuit (MAF): high resistance, short circuit to ground, short circuit to battery + Exhaust gas recirculation circuit (EGR): high resistance, short circuit to ground, short circuit to power VGT drive failure Jamming of the turbocharger blades	Check the mechanical condition of the turbocharger and linkage. Check the condition of the air intake system, make the necessary repairs. Check for sensor DTCs. Check the IAT and MAP sensor circuits. Refer to electrical manual and repair as necessary. Using the data logging function, check the position of the turbocharger actuator. Turn the ignition on, shut off the engine and command the turbocharger actuator to 95% PWM and then to 5% PWM and recheck the position of the turbocharger actuator. The angle at 5% PWM should be in the range 0 - 20%, and at 95% - in the range 80 - 95%. If not, install a new turbocharger. Clear DTCs and check for correct operation.