NCT emissions fail

Violetflame

Hi folks, my 03 Nissan Almera failed the NCT as result of emissions. The readings were as follows:

Low Idle CO .58% above .30% FAIL/REFUSAL
HC 144 ppm above 0 ppm N/A

High Idle Lambda 1.01 PASS

CO .56% above .20% FAIL/REFUSAL
HC 70 ppm above 200 ppm fail

Since the test, I brought the car to a Nissan garage and they told me that it was giving a faulty reading on the back oxygen sensor which could be the cause of failing the emissions test. I told them to replace it.

However, on the way home the engine management light came on. I brought the car back and they reset it and told me it was likely a problem with the catalytic converter.

I brought the car to another mechanic who replaced the cat and thankfully the emissions reading is now fine. However, he said that the sensor should not have been replaced until the cat was examined. Also, he said that the lamba passed the NCT so why replace a sensor based on a computer print out.

Could I please have your views. I paid €290 to have the sensor put in but the mechanic said that if they had looked inside the cat that they would have seen that it was basically redundant as the honeycomb had disappeared.

Any feedback would be appreciated.

fearnatuaithe

Hi folks, my 03 1.4 golf failed on emissions. It did the same last year but put a bottle of clean burn in, drove the hell out of it and got it through on the retest. Tried the same this year and no joy.

These are the readings:
Low idle. CO 0.32. Above 0.30 FAIL

High Idle. Lambda 1.05. Not between 0.97 and 1.03 FAIL
CO 0.27. Above 0.20 FAIL[/B][/B]

I was wondering if anyone knew if these readings would signify the Cat needs replacing? If I replace this does Lambda sensor need to be changed as well?

Car has 147k on the clock but drives like a dream and never gives a days trouble. Any advice greatly appreciated before I go wasting money!

Interslice

fearnatuaithe wrote: »

Hi folks, my 03 1.4 golf failed on emissions. It did the same last year but put a bottle of clean burn in, drove the hell out of it and got it through on the retest. Tried the same this year and no joy.

These are the readings:
Low idle. CO 0.32. Above 0.30 FAIL

High Idle. Lambda 1.05. Not between 0.97 and 1.03 FAIL
CO 0.27. Above 0.20 FAIL[/B][/B]

I was wondering if anyone knew if these readings would signify the Cat needs replacing? If I replace this does Lambda sensor need to be changed as well?
Car has 147k on the clock but drives like a dream and never gives a days trouble. Any advice greatly appreciated before I go wasting money!

CO is marginal - was it fully serviced? - plugs and air filter in particular.

High lambda could be a hole in the exhuast. A vagcom scan would tell you if the lambda sensor is gone.

The coolant temperature sensor would show up on the scan too if it's bust. Common enough fault.

fearnatuaithe

Interslice wrote: »

CO is marginal - was it fully serviced? - plugs and air filter in particular.

High lambda could be a hole in the exhuast. A vagcom scan would tell you if the lambda sensor is gone.

The coolant temperature sensor would show up on the scan too if it's bust. Common enough fault.

Thanks a million for the reply, ya, had a full service only 6 wks ago, had filter and plugs changed . Think I'll get the exhaust checked, could be a small hole letting air in... Cheaper solution than a new cat. The numbers are marginally out so I'm not convinced the cat is the problem... I could well be wrong though!!