Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[bigegg]

If you can get hold of the emissions test results, there is info on the web to decode so you can diagnose the emissions fault.

Goes something like:
high ?? low ?? low ?? Lambda sensor
Low ?? High ?? high ?? Catalytic convertor
low ?? Low ??  low ?? what's the problem?
high ?? high ?? high ?? head gasket/ecu/f***ed

if the cat isn't rattling or heat discoloured, chances are it's the lambda sensor or needs an italian tune-up
second hand lambda sensors are about a fiver (for the only car I've bought one for - a renault scenic) vs. £50 new, at my local scrappie - guaranteed working 

as to the airbag light - might need re-setting, as others have said.
possibly airbag needs replacing - which isn't neccessarily a big, difficult, or expensive job

depends on the car...

[bigegg]

I can't find the site where I pulled the info for diagnosing the emissions readings, but this should give you a good start:
http://www.ratwell.com/mirror/interro/techgas.html

http://www.auto-repair-help.com/auto_diagnostics/diagnose_emission_test_failure.php

[Marks DTM Calib]

An emissions failure can be a whole host of things, no way to make an informed diagnosis based on the results alone.

Similarly, assuming ts the o2 sesnor is a bad move (they rarely fail in practice).

You have to start off by looking at the emission results, is it fast idle, HC failure etc and work from there.

Faults could be many, buggere cat, faulty coolant temp sensor, open thermostat, failing MAF etc etc etc

[bigegg]

they say the best way to get the correct answer on the internet is to post the wrong one 

I've only had solve a failed emissions test once - on the aforementioned Renault Scenic, which was diagnosed as "failed cat" by the MOT-ing garage. 

An italian tune up down the M62 from Hull to Leeds (70mph in 3rd all the way) + a new (2nd hand) lambda fixed it.

[Marks DTM Calib]

You can bet your life it was the italian tune up, you can get many a car through emissions by getting the cat stinking hot

[bigegg]

You cna bet your life it was the italian tune up, you cna get many a car through emissions by getting the cat stinking hot

In retrospect almost certainly.

I bought the car from a single mother who used it exclusively to ferry her children to school and back + a once a week trip to supermarket.  - round trips of 3-4 miles twice a day over two years.

The tune-up wasn't done straight before the MOT, btw - although it was nice and warm when I took it

[omega3000]

You can bet your life it was the italian tune up, you can get many a car through emissions by getting the cat stinking hot

That i can do  Its just on how long the car sits before mot man gets his hands on it 

Thanks for those pointers towards the emissions diagnosis though Bigegg 

[bigegg]

thinking back to the Renault - beware that there is not any other underlying faults which are not mentioned on the MOT.

the reason I mention it:
I bought the scenic as a MOT failure - brakes and emissions.
When I took it for a pre-check at my local garage, cos I didn't trust the garage which did the first MOT.

The brakes, tho low, were not a failure. (changed any way)
The "failed cat" turned out to be fixed as mentioned above.

However, the MOT failed to mention a gaping hole in the sill!

My guess is that the garage which did the MOT was hoping to get the previous owner to pay the £500 to fix the cat and brakes (which it didn't need), then hit her with another £200 for the welding  [1]

any way, moral of the story - have it MOT'd , or at least double checked, by somewhere you trust before you shell out. it may have other, significantly dangerous, faults.

[1]When I told the seller this, she hit the roof. As it was a very small village, and her family owned the local shop/post office, she made sure everyone knew. Last time I went past, the garage was closed down 

[omega3000]

Ive done similar in the past , was quoted £400 from the garage that failed a car then took it to another garage and they passed it  Never have any work done by a garage but you see where folks get ripped off 

[bigegg]

ripped off is one thing, but my mate who does the MOT said that it was a "death trap" - even a low speed impact would have folded it in half.
Garage let her drive away in it.
not funny with three small kids in the car - let alone me driving it 70 miles home!
 

[Marks DTM Calib]

Ive done similar in the past , was quoted £400 from the garage that failed a car then took it to another garage and they passed it  Never have any work done by a garage but you see where folks get ripped off 

I recently looked at the Neighbours daughters Corsa which had failed the MOT on:

Handbrake, low efficiency
Headlight aim low

Advisory on headlight bracket broken.

I checked the handbrake operation and it was very good, so put some greasy finger prints around the steel wheel and tweaked the headlight aim.

It passed with flying colours, handbrake described as very good (nothing done to it!)

[omega3000]

I ran a few days over on an mot so went to a place that could fit me in , no wonder they got me booked in . I intended on asking for a repair quote but little did they know they wouldnt get my money  Garage has since gone out of business . The word soon gets around about rip off merchants 

[TheBoy]

You can bet your life it was the italian tune up, you can get many a car through emissions by getting the cat stinking hot

And a sure way to tell if the cat is really shagged is if it still fails on HC after a proper good 20 mile spanking just before the emissions test  .  Although it passed if the nads were revved off it.

Since replaced cats, as it was getting a bit of an annual saga...

[TheBoy]

Or was it CO?  I'd have to check the MOT failure certs. I have plenty of them 

[Kevin Wood]

I even managed to get my pre-cat codes to disappear for a week by towing a 1.5 tonne trailer tower up onto the downs in Kent at ten tenths earlier in the year.

Mind you, when I then parked it in a grassy field the cats nearly caught the grass on fire.