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Gary Robinson
Gary Robinson, UK Car Mechanic
Category: UK Car
Satisfied Customers: 735
Experience:  Mechanic and MOT tester for 18 years. Excellent knowledge of cars and the MOT testing scheme.
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Peugeot 308 SW: My peugeot 308 SW 1.6HDI 110 engine

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My Peugeot 308 SW 1.6HDI 110 engine management light has come on and displays the message 'depollution system faulty'. I have Googled this fault and I am alarmed by what I am reading with some people allegedly paying hundreds of pounds to rectify the problem. I have just bought the car but the warranty of two months has not long past. Current mileage is around 55,000 miles. I have read a reply by yourself to a similar problem on this site posted two years ago which suggests running the car for 10-20 miles in 4th gear at a constant 60mph. Would this still be the case in your opinion?

The engine management light came on last night on my way to work and immediately lost the power to accelerate normally. The car would still run however. I only noticed the message of 'depollution system faulty' this morning when I turned the ignition back on. The car now accelerates normally but  the engine management light is on and I get the same message every time I switch on.

Your Peugeot is fitted with a diesel particulate filter.

Diesel particulate filters (DPF) are fitted in order to reduce the amount of soot that is produced in diesel engines during combustion.
They have to be cleaned regularly to maintain performance. This cleaning process is called regeneration. The collected soot is burnt off at a very high temperature when an additive is automatically added to the fuel before it is injected into the engine.
Regeneration takes place on long motorway runs, and is controlled electronically by the engine management system.
When the amount of soot in the filter reaches a pre set amount, regeneration should begin. It should be possible to start a complete regeneration cycle by driving for around 15 to 20 minutes and keeping the engine speed over 2500 revs per minute.
If the regeneration is not completed, then the amount of soot in the filter will continue to build, until the dashboard warning light will illuminate, as in this case.
At this point, if a long motorway drive does not rectify the problem, it may be necessary to have a new DPF fitted. Typically, these can cost around £1000, but before this, you should have a diagnostic check carried out which will give a code or codes. These codes will tell your garage where the problem lies.

The only way to avoid these problems is to give your car a good run at motorway speeds once in a while to allow regeneration to be carried out.

I hope this answers your question.

Gary Robinson and 2 other UK Car Specialists are ready to help you
Customer: replied 3 years ago.

Could you also please tell me if it is OK to continue driving the car in the meantime, albeit that the proper acceleration is not there? I can't manage to get to a garage today to get the error code from the engine management.

I tried driving it this morning on the motorway in 4th gear at 60 mph (approx 3000 rpm) for a few miles before the engine management came on again. I could feel a loss in power again but continued to drive for about 20 minutes still in 4th gear. (the revs did drop slightly just below 300 rpm).

Thank you very much for accepting my answer.

You should be ok to continue to drive your car, but I would recommend having the check done as soon as possible.

Hi Derek.
Once again, thank you very much for your question. I hope that you were happy with my answer and that your Peugeot is now running well. If you have more questions, you can ask me directly — that's what I'm here for!
Best regards, Gary.