Tag Archives: diagnostic code read

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.
Split 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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Hyundai I20 Timing Chain Noise.

A customer brought their Hyundai I20 into us to check for an engine noise which they were concerned about.

As soon as the car drove into the workshop we had a good idea what the problem was, it sounded like the timing chain was trying to escape from the engine!

After having a good listen to the engine the next step was to strip off the timing chain cover to allow us to visually check the chain for condition.

With the timing chain cover removed we checked the timing chain, guides, gears and tensioner for wear, the chain tensioner was at full extension and the chain was still loose!

Whilst trying to turn the engine over manually to align the timing marks the chain actually started jumping teeth (it had only been the chain cover stopping this happening whilst driving).

Timing chain cover where the chain had been rubbing!

On inspection of the parts we could see everything was worn to excess and the customer had been very very lucky the chain didn’t slip whilst driving as that would have caused serious engine damage.

Once the timing chain kit had been replaced and the engine rebuilt the car purred as it should.

We later found out the Hyundai I20 had not been serviced for several years and thousands of miles leading to this problem.

Regular servicing using the correct lubricants will prevent premature wear on all engine parts especially chains, guides and gears.

Aarons Autos car service garage.

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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.

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

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Citroen Berlingo with ABS Wiring Fault.

A 2014 Citroen Berlingo came in to us with an ABS fault to be looked at.

First thing to do was carry out a diagnostic code read to see why the ABS light was on, the particular code for this Citroen Berlingo van related to an open circuit on the rear left wheel speed sensor.

We checked the actual wheel speed sensor for a fault but it checked out ok, next job was to check the wiring from the sensor back to the ABS pump.

Most of the wiring for the rear ABS sensors is hard to access as it runs inside the van. once we had determined that there was in fact a break in the wiring from the left rear sensor and the ABS pump (by checking continuity of the wires) it was time to start stripping the interior and physically check the wiring for a break.

After removing the passenger seats and lifting the carpets to access the wiring we noticed part of the raised carpet flooring had been trapping the ABS wiring loom between a raiser and the body and over time had rubbed through the wiring and caused it to short out against the body.

ABS wiring trapped under the carpet.

We repaired the wiring and and rechecked for continuity through the loom which we now had. Time to clear the stored fault codes and check for a wheel speed signal using the live data on our diagnostic scanner, perfect, the signal was good and the same as the rear right wheel, time to rebuild and road test.

Aarons Autos car service garage.

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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.

Basics of the Oxygen Sensor.

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.

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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.

Heater resistor / module

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.