A3 1.8SE GOING INTO LIMP MODE

[Graysilk]

Hi,

I have been running a 2002 A3 1.8SE for the past 15 years with very little trouble. I recently had the cam belt, tensioners and water pump replaced as it was about due. Since then I have had the Engine management light illuminate and the car went into limp mode. I took it to a reliable garage who diagnosed a faulty EGR valve which they replaced. About 120 miles later the engin management light came on again and I took the car back to the garage who ran diagnostics. They infomed me that it was most likely because of a faulty Catalytic Converter but that it wouldnt  be economical to replace it to run the car until the next MOT and that the car wouldnt go into limp mode because of the issue. I drove about 10 miles down the road and the car went into limp mode again. Can anyone please confirm if a faulty catalytic converter would cause the car to go into Limp mode please. Having just spent considerable money on the cam belt and a new EGR valve I am reluctant to throw good money after bad, much as I love the old girl.

Thanks in advance

[Stevey Y]

4 hours ago, Graysilk said:

Hi,

I have been running a 2002 A3 1.8SE for the past 15 years with very little trouble. I recently had the cam belt, tensioners and water pump replaced as it was about due. Since then I have had the Engine management light illuminate and the car went into limp mode. I took it to a reliable garage who diagnosed a faulty EGR valve which they replaced. About 120 miles later the engin management light came on again and I took the car back to the garage who ran diagnostics. They infomed me that it was most likely because of a faulty Catalytic Converter but that it wouldnt  be economical to replace it to run the car until the next MOT and that the car wouldnt go into limp mode because of the issue. I drove about 10 miles down the road and the car went into limp mode again. Can anyone please confirm if a faulty catalytic converter would cause the car to go into Limp mode please. Having just spent considerable money on the cam belt and a new EGR valve I am reluctant to throw good money after bad, much as I love the old girl.

Thanks in advance

Hi the cat would cause that problem, would be worth slinging a bottle of Cataclean in the tank I have used this on several cars I have worked on for friends and neighbours with spectacular results, the problem is the Cat will throw a wobbler if its only running at 95% efficiency and at about £15 a bottle its cheaper if it works than a new Cat, my neighbours Focus has been treated and now runs like a Swiss watch.

Steve.

[Stevey Y]

BTW it could also be the two oxygen sensors one before the cat and one after the cat they also give up codes for a failing cat.

[Graysilk]

Thanks for the advice Steve, I wasnt aware of Cataclean, I'll pop down to Halfords in the morning and give it a go. It that doesnt work I'll take a look at the oxygen sensors.

Once again thanks for the help

[Graysilk]

Halfords did a diagnostic test and there is a EGR fault and also a Cat fault.

Which is strange as I've just had the EGR valve replaced. As Audi are not stocking this part anymore an OEM replacement was fitted. I'm just wondering is it might be defective. Any idea how accurate the diagnostics are? If its coming up with a EGR fault is that definately a faulty valve?

Whilst at Halfords a purcased two bottles of CatClean as I have 2/3 full tank of petrol and have now driven 50 miles without it going into limp mode or the warning light coming on.

Not sure that I would want to go on a long journey with it just yet.

Any advice would be much appreciated

[Steve Q]

If you've had a genuine egr then I'd say it unlikely be that (some after market ones are known to fail within weeks). The warranty on the egr, If done at Audi it should be a year. Could it be the cats as the diagnostic check says I wonder? 

Or as Steve says a sensor. Sometimes sensors fail but instead of diagnostic Bringing up the sensor fault it says there's a mechanism fault instead. 

[Graysilk]

Thanks for your thoughts on this.

I plan on taking the car back to the garage that fitted the EGR valve to sort out. I was quoted 300 pounds for a new Cat from Halfords fitted. 

I'll let you know how it turns out.

[Steve Q]

22 minutes ago, Graysilk said:

Thanks for your thoughts on this.

I plan on taking the car back to the garage that fitted the EGR valve to sort out. I was quoted 300 pounds for a new Cat from Halfords fitted. 

I'll let you know how it turns out.

You're welcome. Even from the garage that fitted it, even if it's aftermarket the egr should have a warranty of some sort. 

[Stevey Y]

2 hours ago, Graysilk said:

Thanks for your thoughts on this.

I plan on taking the car back to the garage that fitted the EGR valve to sort out. I was quoted 300 pounds for a new Cat from Halfords fitted. 

I'll let you know how it turns out.

Hi did the garage that fitted the EGR run the adaptation process, if not that is probably the cause of that fault as the ECU is still working on the information for the failed unit and will not operate properly, the only way to do this is via OBD ELEVEN/VCDS software programs as I am pretty sure Maxxis/ Snap on don't have the facilities presently within their software, seems to be a problem with most generic fault readers.

Steve.

[Stevey Y]

Get the garage to delete both faults and see which one stays as they will probably leave the cat fault so they can sell you a new one.

[Graysilk]

Thanks for those potential problem solutions. I have no idea if the EGR  adaptation process was run, but will certainly ask the question of the mechanic on Monday when I take the car back in.

Just like to say thanks for helping me out on this. At least now I can ask a few questions rather than simply relying on what the garage tells me. Appreciate it.

 

[Steve Q]

23 minutes ago, Graysilk said:

Thanks for those potential problem solutions. I have no idea if the EGR  adaptation process was run, but will certainly ask the question of the mechanic on Monday when I take the car back in.

Just like to say thanks for helping me out on this. At least now I can ask a few questions rather than simply relying on what the garage tells me. Appreciate it.

 

You're welcome, glad Steve & I could help. Please keep us posted on how you get on 🙂