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Front afr/O2 sensor ?

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Old 23 December 2009, 06:32 PM
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shepster
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Default Front afr/O2 sensor ?

Hi just fitted a new denso o2 sensor to cure my hesitation/surging. Drove the car all last night and was fine but now i have a cel light up on the dash even though the car runs fine. Any ideas ??
Car is an 04 wrx running mods.

Thanks

Last edited by shepster; 23 December 2009 at 06:34 PM.
Old 23 December 2009, 09:02 PM
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Jolly Green Monster
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Need error code read, could be unrelated
Old 23 December 2009, 11:24 PM
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Ok cheers, i plan on a trip to the dealer tomorrow as i need some rocker cover gaskets anyway, so hopefully they can shed some light on it. Why do things always happen at once
Old 24 December 2009, 02:44 PM
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Hi, dealer just read codes and it was the front o2 sensor. He cleared the fault and now it all seems to be fine. Any ideas why it triggered after the new one was fitted??

Cheers and merry christmas
Old 24 December 2009, 09:27 PM
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Grrrrrr its back on
Old 24 December 2009, 09:35 PM
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Have you puta de-cat up-pipe on from the manifold to the turbo as tat is what caused my light to come on and even though I replaced the sensor as per Subaru. The light isstill on when I run the OE ecu.
Old 24 December 2009, 10:04 PM
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Hi yea de cat uppipe fitted but have resistor fitted in place of the temp sensor before the turbo to stop the cel light. The rear o2 has had the codes disabled by the mapper.
The light was not on with the old sensor but the car ran bad, now the car runs as it should but with a cel light, im confused!
Old 24 December 2009, 11:35 PM
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is the rear o2 sensor fitted?

the ecu alters the fuelling on the front one and uses the rear to check it is doing as it expected.. if the rear sensor isn't fitted the floating value or a resistor on the plug will be valid value and therefore the ecu may throw a front o2 sensor error as the adjustments it is asking for are no see on the rear sensor..

bit of a long short but if rear is removed I expect you have confused it.,


if by rear sensor cels cancelled you meant the cat fail cels and the o2 sensor is still fitted then ignore me.. lol

Was the remap done possibly with the failed sensor? maf scaling could be wrong if setup low down using the front o2 sensor.. many mods fitted? and how long ago was it mapped?


Simon
Old 25 December 2009, 03:47 PM
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Originally Posted by Jolly Green Monster
is the rear o2 sensor fitted?

the ecu alters the fuelling on the front one and uses the rear to check it is doing as it expected.. if the rear sensor isn't fitted the floating value or a resistor on the plug will be valid value and therefore the ecu may throw a front o2 sensor error as the adjustments it is asking for are no see on the rear sensor..

bit of a long short but if rear is removed I expect you have confused it.,


if by rear sensor cels cancelled you meant the cat fail cels and the o2 sensor is still fitted then ignore me.. lol

Was the remap done possibly with the failed sensor? maf scaling could be wrong if setup low down using the front o2 sensor.. many mods fitted? and how long ago was it mapped?


Simon
Hi Simon, thanks for the reply, yes i meant the codes, the rear sensor is still in place. The car was mapped over a year ago by Bob rawle and has been perfect untill the last few weeks.
Car is running 350/349ftlb, full 3" de cat, manifold, 18g, sti topmount,550 injectors fuel reg etc
all on 97ron

cheers

Last edited by shepster; 26 December 2009 at 11:28 AM.
Old 28 December 2009, 07:49 PM
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Ok now im getting anoyed, cel has now gone out but the car runs like poop again, no power off boost and a juddery/lumpy transition between closed and open loop i guess as it comes onto boost. Any suggestions? Car now has new MAF and a new front Lamba sensor!!

Many thanks
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