EGR Valve Failure. Sometimes the engine does not start or it stops while on the move

In this post we are going to show you a common failure in many 1.6 HDi vehicles with engines developed by the French PSA group. Currently these engines can be used in Citroën and Peugeot 1.6 HDi, Mazda 1.6 MZ-CD, Ford 1.6 TdCi and Volvo 1.6D. 

SYMPTOM:
Sometimes the engine does not start or it stops while on the move.
The engine warning light stays on constantly.

If we proceed to the reading of the fault codes, the following stored codes may be detected:

EGR 1.6 HDi

Depending on the engine, the causes of failures can be different.

In the case of the fault P0698 – Sensor Reference Voltage C – Circuit low, it consists of 5 V power supply from the Engine Unit to a few sensors the most likely problem is the EGR valve is internally shorting the 5 V supply from the engine control unit.

For those vehicles in which the power supply of the throttle position sensor is independent, the fault code that will appear will be P1586.

Some other fault code may appear, but it will probably be caused by the engine stop.
   
DIAGNOSIS:
1-   Verify the power supply voltage of the EGR valve position sensor.
This sensor is incorporated in the electric EGR valve itself. It shares an electrical connector with the EGR actuator command.

A different pin arrangement may be used for the connectors of the different manufacturer. It is recommended to use the wiring diagram of the vehicle manufacturer.

Part of a Wiring Diagram 1.6 HDi (9HZ)

2-   In several occasions, when the vehicle does not start the power supply voltage of the EGR valve position sensor is 0.4 V instead of 5 V. 

For engines that share power supply with other sensors, it is recommended to disconnect the EGR connector and try to start the engine. The car will start with the EGR failure, but the 5 V power supply to the other sensors will no longer be disturbed by the EGR valve sensor.

EGR Valve Location

REPAIR:
Replace the entire EGR valve, as both the EGR actuator and the EGR valve position sensor are part of a common set.