V8 petrol with fault codes

[Thommo]

Hi all, first time so hope this is correct. I fitted a 3" mandrel bent exhaust with high flow cats about three months ago. On Monday I had my engine light come on and then the trc/ vsc and vsc off lights also come on. I had local mechanism ccheck and he said it is a n O2 sensor fault, due to the exhaust. Can anyone shed some light on why it has taken three months to show up? If it is due to system, is there a way of fixing? Thanks in advance

 

[Gav Peter]

Hey Thommo, welcome along

Have you tried fitting a new sensor? Jon Wildsmith should be along soon to offer more constructive advice ;-)

Did you fit new headers & if so, where did you get them from?

Cheers

 

[Thommo]

Thanks Gav. I haven't fitted headers yet, only to keep costs down, but should go on after silly season is over. I will be fitting Geni headers which I think are made here in Australia and fitted for about $1000 all up. The system sounds really tough without any drone on the highway, so very happy with it. I did fit a digital duel battery monitor with amperage display on the afternoon before I got the first code, so still trying to determine if there is a link is coincidence. If I disconnect the battery for a few minutes the lights go out and don't come on for approx 10 km or so. I have been told by many people that this is common with bigger systems and to not worry about it, but can't leave it.

 

[Gav Peter]

Have you had a word with the exhaust supplier?

 

[Thommo]

I will call him today and see what he says. I have been doing a lot of online research and come up with the following.
1- install a spacer under the O2 sensor to reduce the amount of surface contact
2- relocate them further down the system away from the cats
3- ignore the lights or remove bulbs

Is anyone an auto electrician that could answer this? If an O2 sensor puts out a voltage around 1v when working fine could I install either a resister or a capacitor in the wiring to drop the voltage so the ecu will get a reading back within the correct range??????? This is only something I have dreamt up, so may be completely stupid?..

 

[Jon Wildsmith]

Do you know which sensor? There is a pre and post CAT sensor on each bank. Could just be coincidence that you recently had the exhaust done and now a sensor has failed. Could be that the CAT(s) have failed, which is what the post CAT O2 sensor is there to detect I think.

 

[Thommo]

Thanks Jon. Have spoken to exhaust shops, Dyno tuners and mechanics. The Dyno tuner told me that the ecu would have detected the different air flows after new system was installed and tried to correct by adjusting mixture and as it has been unable to get it back within tolerance it has now thrown up the code????? Another mechanic told me that they are sooo sensitive it could have been because I put a bottle of spitfire in the main tank on last fill up? Exhaust shop said I most probably have a faulty O2 sensor as it would have coded before now. This is the issue. I might wait a week and run on normal 91 ulp, then if still coded, find which sensor is coding and replace?? Thanks to all who are helping and welcome any ideas.

 

[Jon Wildsmith]

Thanks Jon. Have spoken to exhaust shops, Dyno tuners and mechanics. The Dyno tuner told me that the ecu would have detected the different air flows after new system was installed and tried to correct by adjusting mixture and as it has been unable to get it back within tolerance it has now thrown up the code????? Another mechanic told me that they are sooo sensitive it could have been because I put a bottle of spitfire in the main tank on last fill up? Exhaust shop said I most probably have a faulty O2 sensor as it would have coded before now. This is the issue. I might wait a week and run on normal 91 ulp, then if still coded, find which sensor is coding and replace?? Thanks to all who are helping and welcome any ideas.

I think the simple explanation is the most likely - a sensor has failed.

 

[Thommo]

Thats what I'm hoping. Will keep you posted.

 

[Thommo]

Hi guys, well after purchasing my own ecu reader, I was able to identify exactly what the code was. It was actually the bank 2 sensor 1 heating coil failure. Replaced sensor and all is good. Thanks everyone for your suggestions.

 

[Gav Peter]

Good to hear its all sorted out