Golf GTI 2000 Emissions problem

sgross75

I took my car this morning for it's retest and it failed on the emissions again. The car was taken back to the garage last week that did the service recently and they could not find anything wrong but did put in an engine flusher/cleaner.
When I spoke to the tester at the NCT he said that it is possibly the catalytic converter that is causing the problem. Is this an expensive part to replace on the Golf ?

Here are the results of the test for interest sake:

Test 1
Engine / Oil Temp 94
Low Idle (730 rpm) CO 1.08 vol%
HC 43ppm

High Idle (3,150 rpm) CO 0.02%
Lambda 1.01
HC 28 ppm


Test 2
Engine / Oil Temp 81
Low Idle (1,000 rpm) CO 2.60 vol%
HC 13ppm

High Idle (3,160 rpm) CO 3.29vol%
Lambda 0.93
HC 67 ppm

Atlantic Dawn

Catalytic convertor can be expensive, probably around a grand.

The high idle test of the first test shows that your cat was working perfectly at that time reducing the CO to almost NIL. Something else is broken and in the long run may damage the cat too.

If your CO is much over 1% (like in the case of 2 out of 4 tests above, the 1st low idle test is marginal) there is no point blaming the cat until the emissions have been reduced to a sane level. A cat in perfect working order can reduce the CO by around 1% or so (i.e. from 1.5%->0.5% or from 3.5%->2.5%). The lambda from the test2 also shows that something tricks the ECU to overfuel, nothing to do with the cat itself.

The garage you took it didn't know how to fix it so you'll need to take it to another one that knows what they are doing. I would start the analysis from the MAF first. Read the dozens of previous emissions threads for more info.

Hal1

I taught the cat convertor gave off a smell when it stopped working? I'd start with changing the oxygen sensor's.