Is that really a faulty cat? - EEC Tech Tip 1

EEC’s Technical Support Co-ordinator, Stuart Still, talks us through an interesting case he recently came across that would have seen the unnecessary replacement of a vehicle catalytic converter.

Picture the scenario: the engine management light has come on and the fault code on display is ‘cat efficiency’. The remedy?

Replace the catalytic converter... or is it? 

This was a situation I was recently presented with by a respected and knowledgeable auto diagnostic technician. I opened the discussion by asking for the emissions values from the 4 gas analyser – he had not done this test as he thought there was no need as the fault code read ‘cat efficiency’.

He carried out the test and reported the values to me, they were: CO @ .04, CO2 @ 14.4, HC 1PPM, O2 @ .00 and Lambda @1.00.

I explained that the cat was OK as these results were perfect. He disagreed, as the pre- cat Lambda sensor was switching correctly but the post-sensor was not. After making contact with a manufacturer of diagnostic equipment and also his local VW dealer, both confirmed it was the cat, and he was advised that if he fitted an OE cat it would solve the problem.

I called a good friend of mine at VW’stechnical head office and he agreed with me that it was not the cat. The values showed that it was working perfectly, so he suggested that I asked the technician a few questions:

Had the pre-cat lambda sensor had the factory modification? 

This can be identified by looking inside the connector. If there are three silver and two gold contacts it would require the modification. The modified unit has five gold contacts. This was the result of VW having problems with bad connections, resulting in the engine management light coming on with a cat efficiency code – on the sensor in question, it had actually been carried out. 

Had any work been carried out on the engine e.g. replacement of the cam chain for example? This could also switch on the cat efficiency code and is common when the cam chain is not fitted 100% correctly. The result can be that the timing is slightly out and small amounts of unburnt fuel get to the cat, causing a fault code to appear in the ECU memory. 

There may not be a specific fault code in the ECU memory for this particular fault and in this situation the ECU would use the nearest fault code for the problem e.g. ‘cat efficiency too low’.

What did switch the cat efficiency light on? It was actually an intermittent fault which would have only needed to occur for a millionth of a second to switch the light on! Or a very slight air leak on intake side and the engine ECU can see there is a fault and tries its best to compensate for it

How to check

Erase the fault. If the light comes back on after three ignition cycles (i.e start engine and run for 1 min then turn off) you will know that it is a constant fault, if it stays off longer it is usually an intermittent fault (on VW/Audi). 

Most diagnostic machines now log the time, date, engine speed and amount of times the fault occurred to help it. It can’t be the cat as it is working perfectly, see the values.

EEC has embarked on a full emissions training program to include catalytic converters, Lambda sensors, exhaust systems, and how to read and understand 4 gas analyser values. 

These training programs can be arranged through the day or in the evening. To find out how you can take part you can contact Stuart Still or Duncan Richards at sales@eurocats.co.uk

Is that really a faulty cat? - EEC Tech Tip 1

EEC’s Technical Support Co-ordinator, Stuart Still, talks us through an interesting case he recently came across that would have seen the unnecessary replacement of a vehicle catalytic converter.

Picture the scenario: the engine management light has come on and the fault code on display is ‘cat efficiency’. The remedy?

Replace the catalytic converter... or is it? 

This was a situation I was recently presented with by a respected and knowledgeable auto diagnostic technician. I opened the discussion by asking for the emissions values from the 4 gas analyser – he had not done this test as he thought there was no need as the fault code read ‘cat efficiency’.

He carried out the test and reported the values to me, they were: CO @ .04, CO2 @ 14.4, HC 1PPM, O2 @ .00 and Lambda @1.00.

I explained that the cat was OK as these results were perfect. He disagreed, as the pre- cat Lambda sensor was switching correctly but the post-sensor was not. After making contact with a manufacturer of diagnostic equipment and also his local VW dealer, both confirmed it was the cat, and he was advised that if he fitted an OE cat it would solve the problem.

I called a good friend of mine at VW’stechnical head office and he agreed with me that it was not the cat. The values showed that it was working perfectly, so he suggested that I asked the technician a few questions:

Had the pre-cat lambda sensor had the factory modification? 

This can be identified by looking inside the connector. If there are three silver and two gold contacts it would require the modification. The modified unit has five gold contacts. This was the result of VW having problems with bad connections, resulting in the engine management light coming on with a cat efficiency code – on the sensor in question, it had actually been carried out. 

Had any work been carried out on the engine e.g. replacement of the cam chain for example? This could also switch on the cat efficiency code and is common when the cam chain is not fitted 100% correctly. The result can be that the timing is slightly out and small amounts of unburnt fuel get to the cat, causing a fault code to appear in the ECU memory. 

There may not be a specific fault code in the ECU memory for this particular fault and in this situation the ECU would use the nearest fault code for the problem e.g. ‘cat efficiency too low’.

What did switch the cat efficiency light on? It was actually an intermittent fault which would have only needed to occur for a millionth of a second to switch the light on! Or a very slight air leak on intake side and the engine ECU can see there is a fault and tries its best to compensate for it

How to check

Erase the fault. If the light comes back on after three ignition cycles (i.e start engine and run for 1 min then turn off) you will know that it is a constant fault, if it stays off longer it is usually an intermittent fault (on VW/Audi). 

Most diagnostic machines now log the time, date, engine speed and amount of times the fault occurred to help it. It can’t be the cat as it is working perfectly, see the values.

EEC has embarked on a full emissions training program to include catalytic converters, Lambda sensors, exhaust systems, and how to read and understand 4 gas analyser values. 

These training programs can be arranged through the day or in the evening. To find out how you can take part you can contact Stuart Still or Duncan Richards at sales@eurocats.co.uk

Getting charity back on the road

A charity that helps transport people living with cancer in Devon can resume its vital work, thanks to European Exhaust and Catalyst.

The catalytic converter on a minibus belonging to the Sidmouth Living with Cancer group has been recently stolen, as part of an increasing number of thefts across the UK, leaving the charity unable to support many people.

EEC heard about the theft whilst visiting a motor trade show in Exeter through the local media, and decided to help.

Duncan Richards, Sales Director, European Exhaust and Catalyst, said: “As the only UK aftermarket manufacturer of the catalytic converter that fits the Living with Cancer minibus, we were happy to donate the part to ensure the charity could get back to doing their vital work in the community as quickly as possible.”

“It’s terrible to hear that a cancer charity that relies on their transport has been targeted by thieves. As the cost of motoring continues to rise and funding is being reduced for crucial projects like these, charitable organisations are struggling to find the money to replace stolen parts.”

Alan Matthews, Lead Driver from the Sidmouth Living with Cancer charity commented: “Our minibus has only been on the road for the last three months, and was bought through generous donations by everyone in the town. We were told there would be a long wait for an expensive new catalytic converter, but thanks to EEC we can now get quickly back on the road helping the community.”

The theft of catalytic converters is significantly rising, due to the value of the precious metals inside the units, such as platinum, palladium and rhodium, and has increased especially in vehicles that have easily accessible underside catalytic converters.

European Exhaust and Catalyst (EEC) is the largest manufacturer of aftermarket catalytic converters in the UK, supplying independent dealers and motor factors across Europe. The company is based in Denmead, Hampshire with four locations across the UK.

For further details, please visit www.eurocats.co.uk or call 02392 9224 5300.

Training in Ireland

Our Technical Support Co-ordinator Stuart Still has been to Londonderry to discuss Cats, DPFs and emissions testing.

If you'd be interested in some training opportunities for your stakeholders, why not get in touch with us? Email sales@eurocats.co.uk

In the office

Just testing out this great service so we can bring you loads of exciting content.

Diagnosing Diesel Smoke

Soot's exact composition is difficult to characterize because of the different engine technologies and conditions that produce different types of soot. 


Indeed, the smoke from diesel engines can even have different colours. 


For example, blue smoke (mainly oil and unburnt fuel) can indicate a poorly serviced and/or tuned engine; black smoke (soot, oil and unburnt fuel) can indicate a mechanical fault with the engine; and white smoke (water droplets and unburnt fuel) is produced when the engine is started from cold and may disappear when the engine warms up, if it continues it could relate to a head gasket problem.

For more technical advice, visit http://www.eurocats.co.uk/