TECH MAIL: Engine check lamp

By: WebmasterAdmin

I have a 2007 Peugeot 207 1,4 HDi with 74 000 km on the clock, which I bought second-hand from a dealership in February. Since then, once a month an alarm goes off in the instrument cluster and is accompanied by a check-engine light. At the same time, a warning on the information panel reads “anti-pollution faulty”. The engine then appears to enter into limp-home mode.

I returned the vehicle to the dealership and, after investigation, it concluded there was a problem with the exhaust-gas recirculation valve (EGR) and replaced the electronic actuator. The problem went away temporarily, but then returned.

This time, after start-up, the engine jerked and missed, and then died. Once I got the engine running again, it had no power and smoked. Even now, when the engine appears to be fine again, the fuel consumption is much higher than before. What’s the cause?

TIAN WILLEMSE
Hartenbos

Answer: The engine-check lamp (the message is Peugeot specific) is a legal requirement of OBDII and EOBD legislation. This involves the diagnostic system (in the ECU) that monitors all the sensors, actuators and systems of the powertrain. When a failure is detected that may result in the tailpipe emissions exceeding the legal threshold, the engine-check lamp illuminates. There are several faults that are linked to this warning on a diesel engine, and can include:

•    Manifold-air-pressure (MAP) sensor;
•    Mass-airflow sensor (MAF);
•    Exhaust-gas-recirculation (EGR) valve;
•    Boost-control problem (turbo or         air leak);
•    Fuel supply or injector related issue;
•    Blocked diesel-particulate filter (DPF) in the exhaust (if fitted).

The advantage of the OBD system is that a fault code is logged in the ECU’s memory when the light is illuminated on the dash. Therefore, the dealership can plug in its diagnostic tool and read
the code, which pin-points the issue. It may very well still be the EGR valve that is faulty or sticking, but you will know only once the diagnostic trouble code (DTC) is read.

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