Tag Archives: diagnostics derby

Mercedes-Benz A200d with excessive Carbon Build Up In its 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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2017 Audi TT 1.8 TFSI With Fault Code P00b7 – Fixed.

This Audi TT was brought into the Garage with its Engine Management Light (EML) on, after carrying a Diagnostic Code Read we could see numerous codes in its ecu the main one for us was P00b7 which related to poor coolant flow!

When checking the live data we could see that the engine coolant temperature sensor was reading at over 100 degrees whilst the radiator temperature sensor was at a stable 40/45 degrees even after a road test.

The cooling system on this car is controlled by an electronic thermostat which is built into the back of the water pump housing located under the inlet manifold.

To access the water pump housing we removed the inlet manifold for ease, once the manifold was off we removed the water pump and housing for inspection.

When we removed the cover off the electronic thermostat we could see that the gear on the operating motor had broken off meaning that it couldn’t open the thermostat.

The Fix

Using genuine Audi parts we replaced the water pump and water pump housing along with its drive belt then rebuilt the engine so that we could retest for operation.

After running the engine up to temperature we rechecked our live data, the engine temperature sensor was now reaching 98 degrees and then dropping as the thermostat opened and we could see the radiator temperature increase too.

Once the car had been road tested and rechecked for leaks it was handed back to its owner.

Aarons Autos car service garage.

Your friendly car garage in Derby

Give us a call at Aarons Autos for more info.

Volkswagen Scirocco with a leaky Inter-cooler.

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.

Big Strip Down To Remove The Inter Cooler.

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.

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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.

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

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.

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.

More cleaning may be required!

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.

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.

Broken Catalytic Converter On This Vauxhall Mokka.

A Vauxhall Mokka came into the garage today with its engine management light on in need of some diagnostic work to find out the reason why.

After speaking to the customer we soon found out that we were not the first Garage to look at the Mokka.

It had gone into another garage who had replaced the ignition coil pack due to diagnostic trouble codes relating to cylinder miss fires, the coil pack cured the problem and the customer left happy.

After a couple of days the engine management light came on again so back to the Garage she went.

This time the diagnostic codes related to Oxygen sensor (lambda) faults? But rather than checking live data on the scan tool or checking the sensors with an oscilloscope they proceeded to change the sensors and clearing the fault codes to turn off the engine management light.

After another couple of days the light came on again but rather than take the car back to the same garage the customer looked on Google and found us, gave us a call and got herself booked in.

Once the car was in our workshop we plugged in our Diagnostic scanner and carried out a full code scan of the vehicle, all modules were clear of codes except for the Engine Control Module (ECM) which had codes relating to ‘Oxygen sensor faults’.

We then carried out some live data testing on the Oxygen sensors to see what was happening, straight away we could see a problem, both Oxygen sensors were reading the same, this is not good!

Both Oxygen sensors showing the same pattern.

The basics of Oxygen sensors are that they read the gases which are being produced by the engine before and after the Catalytic Converter, and if the Catalytic Converter is working correctly the first sensor should be switching and the second sensor should be pretty static (on idle), if this is happening then the gases coming out of the Cat are cleaner than the gases going in to the Cat meaning lower carbon emissions.

Once we had checked the Oxygen sensors were working properly (not giving false readings) we needed to check the Cat’s internals to see why it wasn’t working.

With the Cat removed it was obvious why we were getting the same readings on our live data, the honey comb centre of the Catalytic Converter which catches and burns off the carbon from the engine had broken up and was allowing the gasses to pass by.

The Catalytic Converter had broken inside.

A new Cat was fitted and we ran another scan, this time no codes returned and the Oxygen sensors were working as they should.

Both Oxygen Sensors now reading as they should.

The customer now has a car which is working as it should, more economical and with a lower carbon output.

Aarons Autos car service garage.

Your friendly car garage in Derby

Give us a call at Aarons Autos for more info.

Citroen DS3 Cooling Fan module / Resistor Fault.

This little Citroen DS3 came into us to have a look at due to the engine cooling fan running at full speed.

Firstly we carried out a Diagnostic Code Read on the vehicle, this didn’t help as it had no codes for anything let alone for the cooling fan fault!

Secondly through our Diagnostic Scanner we can operate certain modules on the engine to help us fault find, one of the modules is the high and low speed cooling fans.

When we operated the cooling fans only the high speed fan would work, this gave us a place to start, we removed the cooling fan control module to find that the resistor for the low speed fan had burnt out and required replacing.

When we rang the dealer they had six on the shelf! Always a good sign as common problem parts are always well stocked at dealerships.

Once we had replaced the cooling fan control module (resistor) we carried out another module test using our Diagnostic Scanner and it worked perfectly on low speed and high speed.

After a quick road test to make sure the fans worked with the air conditioning and when the DS3 was up to temperature it was time to hand it back to a very happy customer.

Aarons Autos car service garage.

Your friendly car garage in Derby

Give us a call at Aarons Autos for more info.