This VW Scirocco came into us with an intermittent running fault, it would randomly put the engine management light on and go into limp mode.
Firstly we carried out a diagnostic code read to see if there were any stored codes and what they related to?
Several codes were stored relating to faults in different systems! Oxygen sensor, Boost pressure and EGR system.
We decided to carry out a smoke test on the intake system as all of these faults can be affected by an air or boost leak.
(A Smoke Tester fills a system with lightly pressurized smoke allowing the user to see any small leaks that may not be obvious to the naked eye.)
We found a leak from around the inter-cooler area but the car needed stripping further to be able to access this area, once the bumper had been removed we could see clearly that there was a split in the inter-cooler housing which was small enough to allow the car to still run reasonably well but bad enough to throw out several sensor readings.
After we replaced the inter-cooler and cleared all related fault codes we carried out a road test and checked live data, all sensors were reading as they should and the car drove perfectly without putting the engine management light on and no more limp mode.
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.
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.