EGR System Failure

NAME OF CODE
EGR System Failure

WHEN MONITORED
With the engine running and engine temperature above 140° F. but less than 210° F, intake air temperature is more than 20° F. but less than 170° F.

SET CONDITION
Once all the conditions are met the EGR is turned on. The Intake Air Temperature Sensor signal is monitored for changes in its output signal during the EGR operation. If no significant change is seen a trouble code is set.

THEORY OF OPERATION
The EGR system recirculates exhaust gases back through the intake manifold to lower combustion chamber temperatures and promote even flame distribution in the combustion chamber. This reduces NOx emissions. The EGR valve is controlled by through the EGR solenoid/Transducer. The Powertrain Control Module controls the solenoid.

POSSIBLE CAUSES
- Open or blocked vacuum supply to the EGR valve
- Blocked exhaust transfer tubes to the intake manifold
- Failed EGR valve
- Failed PCM
- Connectors and terminals
- Failed EGR solenoid/transducer