Oxygen Sensor Probelm

Started by aluk49, October 20, 2016, 11:30

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aluk49

October 20, 2016, 11:30 Last Edit: January 1, 1970, 01:00 by Guest
Hi

Can anyone advise me please.  Car just failed MOT on high emissions  s:-( :-( s:-(

Lambda reading was 1.068 (Limits 0.970 to 1.030)
Does anyone know which sensor is used to control Air/Fuel Ratio please?

Thanks

Al

Topdownman

#1
October 20, 2016, 12:05 Last Edit: January 1, 1970, 01:00 by Guest
Are you getting any error codes? Normally you would have the EML on if there was a problem with a sensor.

Did the garage suggest what could be wrong or what to check?
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Ardent

#2
October 20, 2016, 12:14 Last Edit: January 1, 1970, 01:00 by Guest
does the engine check light come on when you turn the ignition on, then go off after a second or so when engine is running.
As above, unusual NOT to have an eml light if sensor is poorly.

Was engine properly up to temp before the test.
If you install Torque pro on atablet and get a bluetooth dongle you will be able to monitor the sesnors switching. If they are, problem elsewhere.

loadswine

#3
October 20, 2016, 13:52 Last Edit: January 1, 1970, 01:00 by Guest
Often a maf clean and a quick blast can bring thngs within limits.
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aluk49

#4
October 20, 2016, 16:13 Last Edit: January 1, 1970, 01:00 by Guest
Thanks All,

No lights showing and no error codes showing up on my reader.  took it Halfrauds for MOT, they were no help in diagnosing the problem.  But they did agree to me giving it a good run to heat it up, but it still failed.  Will try cleaning the MAF and get a mate to check outputs over the week-end.

shnazzle

#5
October 21, 2016, 09:18 Last Edit: January 1, 1970, 01:00 by Guest
o2 can send totally duff figures to the ECU without causing an EML. This would shoot off your lambda readings.
I've had this twice now. One was a brand new Denso post-cat sensor,few months old. Ended up being the cause of some severely crap running.

Clean maf, reset ECU, take it for a blast and check o2 sensor readings.
...neutiquam erro.

PhilzMR2

#6
October 21, 2016, 16:21 Last Edit: January 1, 1970, 01:00 by Guest
Check for leaks in your cooling system (duff radiator etc). It's important that the engine is running at the correct temperature and the ECU has an accurate temperature reading.

Mine was struggling with emissions until I changed a leaking radiator and replaced a faulty post cat sensor which was lighting the EML. Everybody tells me the post cat sensor isn't part of the closed loop system, in which case it can only have been the radiator causing the problem.

Definitely worth checking to see if you are losing any coolant.

Bongo

#7
October 21, 2016, 20:31 Last Edit: January 1, 1970, 01:00 by Guest
I once had a loose O2 sensor causing an emissions failure. Once it was refitted properly all was good again.

If you've had any of them undone it could be worth double checking.

jonbill

#8
October 21, 2016, 20:40 Last Edit: January 1, 1970, 01:00 by Guest
High lambda reading means more 02 present than expected right? so a loose/missing pre-cat 02 sensor (as above, badly fitted crush gaskets or any other leak in the exhaust could be the source. maybe

beavisrules

#9
October 21, 2016, 21:00 Last Edit: January 1, 1970, 01:00 by Guest
how long since last oil/fuel/plugs/air filter were serviced.?
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