Tag Archives: dpf fault

Mercedes-Benz A200d Carbon Build Up In Engine.

This Mercedes A200d with the 2.1 diesel engine came into us for a Diagnostic Code Read because its EML (Engine Management Light) was on.

The Codes were –

  • P0401 Exhaust gas recirculation (EGR) system – insufficient flow detected
  • P0638 Throttle actuator control (TAC), bank 1 – range/performance problem
  • P200A Intake manifold air control actuator, bank 1 – performance problem

After checking some of the live data we decided to remove the EGR pipe to have a look inside the intake system, the system was full of carbon build up which was causing blockages.

After speaking to the customer we found that he only uses the car for short journeys and it very rarely gets a long run.

We are seeing this as a weekly occurrence at the moment, modern diesel engines are not designed for lots of short journeys they are more designed for long distance commuting.

When a modern diesel engine is driven on a long journey it carries out a DPF (Diesel Particulate Filter) regeneration which basically means it cleans out the exhaust system of carbon and soot build up, the same carbon and soot is found in the engine and long journeys help to clean that too.

Once we had cleaned out the intake and EGR system we cleared all stored engine codes and took the Mercedes for a long road test, upon return we carried out another Diagnostic code read and none of the codes had returned and all live data was reading correctly.

The car was given back to its owner and we also advised him to go on at least one long drive per week or the car would be back to us with the same fault.

Aarons Autos car service garage.

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Give us a call at Aarons Autos for more info.

EGR blocked on this Renault Traffic.

This Renault Traffic came into us with its EML (engine management light) on and had a lack of power.

The first job was to carry out a diagnostic code read which showed up several codes relating to EGR valve faults.

As it is quite a big job we needed to get authorisation from the customer to remove the front end off his van access the EGR valve.

Once we had removed the front end we could access the EGR valve and start to remove it, once removed we could see the problem.

Completely blocked EGR valve.

The EGR valve and pipes were completely full and blocked with carbon deposits which was stopping the valve from working properly.

Blocked EGR pipes.

We replaced the EGR valve and cleaned out all the pipes to and from the valve, this cleared the codes and allowed the vehicle to drive at full power.

New EGR fitted.

Unfortunately due to the amount of carbon build up in the pipes we determined that the rest of the intake system would have similar carbon deposits in them and may need cleaning in the future.

We advised the customer to take the van on several long journeys at an average RPM of 2500 this will allow the engine to carry out a regeneration of the DPF (diesel particulate filter) and help clean out carbon deposits from the intake system.

This will no doubt have to be carried out several times to get the engine into a good internal condition.

The biggest problem with modern diesels is that people drive them economically and on short journeys, this is what causes the carbon deposits to build up and cause issues, ideally they should be used for long journeys at least once a week to allow the engine to clean itself.

For more info on EGR or DPF faults don’t hesitate to contact us.

Aarons Autos car service garage.

Your friendly car garage in Derby

Give us a call at Aarons Autos for more info.

Golf / Jetta TDI with DPF and boost faults.

This Volkswagen Jetta came into us with its engine management light, DPF light and glow plug light illuminated. It had very little power and needed some attention.

Firstly we carried out a diagnostic code read to see what fault codes were causing the light to be on, several codes relating the Diesel Particulate Filter (DPF) being blocked or soot content to high and one relating to boost pressure lower than expected.

Next we tried to clear the codes and restart the car to find out which codes stayed live, in this case all the codes stayed.

We tried to carry out a Diesel Particulate Filter Regeneration which with this particular car has to be done whilst driving.

You have to drive the car in 4th or 5th gear at approximately 2000 rpm until the DPF light goes out, this can take up to 40 minutes depending on how blocked the DPF is.

The regeneration did not work, so back to the workshop for some more tests.

We tested the differential pressure before and after the DPF, this is done using a pressure gauge which is connected on to the pressure sensor pipes, if the pressure is to high the DPF wont allow you to carry out a regeneration and the DPF will need to be cleaned out using chemicals either on or off the car.

The DPF soot content on this Jetta was very high so we decided to remove the DPF and have it chemically cleaned.

DPF removed from car.

Whilst the DPF was off we decided to check in to why we were getting a code for low boost pressure, we checked the turbo actuator pipes for leaks which all seemed ok then we checked to see if the actuator was working using a vacuum tester, the actuator wouldn’t hold vacuum.

We removed the turbo actuator and tested it against a new one (see the video below)

Once the DPF had been cleaned out and we had replaced the faulty turbo actuator it was time to retest the the car.

We cleared the codes and took it for a road test, all the warning light extinguished and we had full power, brilliant.

After speaking to the customer we realised that the car had lost power several months ago and he didn’t have it looked at until now due to the fact of not just one warning light being on but three on the dash.

The car wouldn’t carry out a driven regeneration of the DPF (which they do regularly under normal circumstances) due to the faulty turbo actuator which then caused the DPF soot content to increase until it was full causing all the warning lights to come on.

The Moral of this story is ‘Warning lights are important‘ if you have a warning light come on on your car get it checked out before it causes any more damage.

Aarons Autos car service garage.

Your friendly car garage in Derby

Give us a call at Aarons Autos for more info.