NCT Fail Emissions

SCOOP 64

My Astra g 1998 1.4 petrol faiedl on emissions , the nct man advised me that hes pretty sure its not the Catalytic convertor as the emissions come in and out and said most of the time this would be Lamda Sensor , first time i have ever got advice from nct staff, usually just say it fail and tell you what on, but i think he maybe right was getting a intermittent fault code p0170 02 sensor open circuit, any second opinions on this?

Seweryn

The values are marginally above the limit.

When was the service done including the spark plugs and air filter replacement?

I think a bit of care plus 30 min. of steady motorway drive should sort this out.

CoBo55

https://www.boards.ie/discussion/comment/118221378#Comment_118221378

It's 50% over the limit on the high rpm test. If it has been serviced he'll struggle to get it down. I wonder what the general health of the engine is like, compression etc?

SCOOP 64

Car is running well, was driver for 45 minutes hard run before test, oil change in July, spark plug change last year, air filter 2 yrs old, car was over a pit last week no leaks in exhaust, i will change the Lamda sensor as recommended by nct guy ( but Lamda was a pass?) as this was throwing a code anyway, and run it in again.

Always change oil day(s) or week before NCT. Air filter is not so expensive, replace every year.

SCOOP 64

https://www.boards.ie/discussion/comment/118222711#Comment_118222711

Reading the above could Lamda sensor be the problem? thanks

Sorry, I do not comment that because car is old and engine health is unknown.

ronaneire

Change the air filter and a new set of spark plugs. They are not that expensive.

Atlantic Dawn

The Lamda sensor while cheap and relatively easy to fit can be an absolute nightmare to take out the old one, sometimes requiring heat to bring it out. I'd stick with purchasing an original Opel/Vauxhall OEM sensor so it's just plug and play rather than having to splice/solder wires in spurious brand.

Have you checked the exhaust for any leaks in it, might be noticeable as muffled noise when car idling, that can sometimes throw up similar errors.

SCOOP 64

https://www.boards.ie/discussion/comment/118222978#Comment_118222978

i brought a Bosch Lamda sensor the connections are the same , car was over a pit last week could see no leaks from exhaust.

CoBo55

https://www.boards.ie/discussion/comment/118223005#Comment_118223005

Did you check the emissions since fitting the new sensor?

SCOOP 64

https://www.boards.ie/discussion/comment/118223197#Comment_118223197

I haven't fitted it yet will do at weekend.

Atlantic Dawn

https://www.boards.ie/discussion/comment/118223503#Comment_118223503

Yes not sure if you have done one before or not but there's specific sockets you can get to remove/fit them, makes life easier, could be worth getting one. I think the sizing is universal but I'm not 100%...

https://www.halfords.ie/tools/hand-tools/laser-oxygen-sensor-socket-22mm-3%2F8%22-drive-221892.html

funnyname

Dipetane added to the fuel will help

SCOOP 64

https://www.boards.ie/discussion/comment/118223722#Comment_118223722

yes i brought one of those from Amazon because ive been told it can be a nightmare to undo will give a good spray with WD40 too.

SCOOP 64

https://www.boards.ie/discussion/comment/118223787#Comment_118223787

Would dipetane need to be in tank at time of test or run it a few days before with dipetane then go in with just petrol in tank?

funnyname

I used to put in a bottle with a full fill and run it for about a half a tank before the test with a good hard run on the day of the test.

Failed emissions once, never failed after doing this.

SCOOP 64

Changed the Lamda sensor today i got lucky off and on in 5 minutes did spray wd40 on it last 2 days, ratchet wouldn't move it so used a bar on ratchet and it came loose ,thought id broken it off at first because i didn't use that much pressure, also Dipetane in tank now, booked in for retest Friday 8.30pm, hope that its but with emission's never that simple,(That Lamda socket tool worth it).

CoBo55

Good stuff let us know how it goes.

SCOOP 64

Passed 😀 ,get too keep it on road for another year, had it for 14 years now.

CoBo55

Brilliant 👍

Thanks for the update.