Failed nct exhaust emissions

natzc · 12-09-2014 9:19am #1

Hey im going to go insane so if anyone can help id much appreciate it,

I drive a 03 1.2 polo (i think 4 cylinder engine)

I have replaced cat and front oxygen sensor, put in petrol cleaner stuff and drove the **** out of it before the test to have the engine hot but the car is still failing emmissions.

The engine amber light is on, iv had it connected up to a diagnostics system twice now which was what told me to replace the o2 sensor. Cleared the faults and then it pops back up. ðŸ˜

The fella in the nct centre said its throwing up false readings.

Heres the fail sheet info

Low idle: (703rpm) engine oil temp: 95°
Co2 : 0.48% (LIMITS ABOVE 0.30% FAIL) FAIL
hc: 185ppm (LIMITS ABOVE 0PPM FAIL)n/a

High idle: (3218) lambda:0.90 (LIMITS not between 0.97 - 1.03) Fail
Co2: 2.54 vol % (LIMITS ABOVE 0.20%) FAIL
Hc: 839ppm (LIMITS ABOVE 200PPM) FAIL

Any help much appreciated i dont know what else to do and dont have a whole lot of money left to pump into this pain in the h*le

jimgoose · 12-09-2014 11:21am

What exact fault codes are showing up in the diags? That thing is running outrageously rich. Can you smell the exhaust? Is it idling OK? At this point I'd suspect a problem with MAP sensor, causing it to misreport airflow and thus confuse the whole setup.

natzc · 12-09-2014 1:41pm

jimgoose wrote: »

What exact fault codes are showing up in the diags? That thing is running outrageously rich. Can you smell the exhaust? Is it idling OK? At this point I'd suspect a problem with MAP sensor, causing it to misreport airflow and thus confuse the whole setup.

Cant smell exhaust but ur man at the nct center said it wasnt idling right in higher gears i think he said but i cant really remember he could have said low gears either....i never noticed it though...

jimgoose · 12-09-2014 1:52pm

natzc wrote: »

Cant smell exhaust but ur man at the nct center said it wasnt idling right in higher gears i think he said but i cant really remember he could have said low gears either....i never noticed it though...

High revs, I expect he said. And/or low revs.

Chimaera · 12-09-2014 1:53pm

I think your best bet here is find a good mechanic.

natzc · 12-09-2014 1:54pm

natzc wrote: »

Cant smell exhaust but ur man at the nct center said it wasnt idling right in higher gears i think he said but i cant really remember he could have said low gears either....i never noticed it though...

And the fault codes were saying bank 1 02 sensor so thats y i replaced

natzc · 12-09-2014 1:55pm

natzc wrote: »

And the fault codes were saying bank 1 02 sensor so thats y i replaced

Ha yeah iv a head like sieve sorry

Ascii · 12-09-2014 2:09pm

could the lambda sensor be gone in it ?

jimgoose · 12-09-2014 2:12pm

OP, what I would personally do is clear the codes using a handheld scanner, then unplug the MAP sensor and give it a few gentle start/drive/shutdown cycles to see if the codes stayed away. But as Chimaera says, you need a good mechanic.

Ascii wrote: »

could the lambda sensor be gone in it ?

The Lambda was already changed in it.

natzc · 12-09-2014 2:56pm

jimgoose wrote: »

OP, what I would personally do is clear the codes using a handheld scanner, then unplug the MAP sensor and give it a few gentle start/drive/shutdown cycles to see if the codes stayed away. But as Chimaera says, you need a good mechanic.

Il give this a go thanks....im reluctant to put any more money into it at this stage incase it doesnt solve the problem....would an emmissions test at a garage be anygood in identifying the problem or would it still be a bit of a guessing game

jimgoose · 12-09-2014 3:07pm

natzc wrote: »

...Il give this a go thanks....im reluctant to put any more money into it at this stage incase it doesnt solve the problem....would an emmissions test at a garage be anygood in identifying the problem or would it still be a bit of a guessing game

You need a competent mechanic who is capable of performing a proper component-level debug-and-diag on these kinds of problems.

George Dalton · 12-09-2014 3:41pm

Looking at those HC figures and given the fact is is an 11 year old 1.2 Polo I would say the most likely cause is that is it burning oil and needs an engine rebuild or replacement.

John T Carroll · 12-09-2014 9:38pm

natzc wrote: »

Hey im going to go insane so if anyone can help id much appreciate it,

I drive a 03 1.2 polo (i think 4 cylinder engine)

I have replaced cat and front oxygen sensor, put in petrol cleaner stuff and drove the **** out of it before the test to have the engine hot but the car is still failing emmissions.

The engine amber light is on, iv had it connected up to a diagnostics system twice now which was what told me to replace the o2 sensor. Cleared the faults and then it pops back up. ðŸ˜

The fella in the nct centre said its throwing up false readings.

Heres the fail sheet info

Low idle: (703rpm) engine oil temp: 95°
Co2 : 0.48% (LIMITS ABOVE 0.30% FAIL) FAIL
hc: 185ppm (LIMITS ABOVE 0PPM FAIL)n/a

High idle: (3218) lambda:0.90 (LIMITS not between 0.97 - 1.03) Fail
Co2: 2.54 vol % (LIMITS ABOVE 0.20%) FAIL
Hc: 839ppm (LIMITS ABOVE 200PPM) FAIL
Any help much appreciated i dont know what else to do and dont have a whole lot of money left to pump into this pain in the h*le

I know this sounds a bit simplistic but thats where I always start, with the simple things. Try a new set of spark plugs. You might also like have a read of one of my last posts under "VW Golf 1.4 Emissions Fail".
A friend of mine who still owns a 3 cylinder 03 1.2 Polo failed the NCT test last year on Emissions, the car had 120K miles up and was using about 1 litre oil per 700 miles, the failed readings were at oil temp 98C and Rpm: 750. CO: 0.95%. HC:62 PPM. High Idle: Lambda:0.93. CO: 2.03%. HC: 370 PPM.

He renewed the spark plugs and the retest were Low Idle: CO:0.23%, HC:159 PPM. and High Idle. Lambda:1.01. CO:0.21%. HC:127 PPM. PASS.

You have nothing to lose by doing this, if you have not done so already. You can buy a set of relatively "cheap" (not long life) spark plugs for around €20.

natzc · 15-09-2014 12:19pm

George Dalton wrote: »

Looking at those HC figures and given the fact is is an 11 year old 1.2 Polo I would say the most likely cause is that is it burning oil and needs an engine rebuild or replacement.

I hope not! Il post back if the problem gets figured out thanks for the posts

homingbird · 15-09-2014 9:03pm

Well Known that the nct floor a certain amount of cars to meet their daily quota of fails happened to my brother inlaw .

V.W.L 11 · 15-09-2014 9:05pm

George Dalton is your man for advice,i had a bora fail on the emissions in july,the engine required a rebuild,i got shot of it that night!!!!!!

Failed nct exhaust emissions

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