Engine Light On

[ELFMAN]

As far as I know, all my sensors are original BMW parts. Audrey - I'll keep you posted!

[C.Noble]

Thanks for all your replies Elfman hope you get your light problem fixed post it up and let me know

I dont know if you are into the racing too, or if you are likely to be passing through Fife, but if you are, give me a shout, I can do a quick code read on your MINI too if you want.

[audrey]

Never been to the racing Fife is quite a drive away from me but thanks for the kind offer and taking the time to give me advice been really helpful much appreciated.

[audrey]

CN The fault code was p0131.Put the car in yesterday for a service.Same code came up again but as the sensors have both been replaced he had an electrician take a look at it.The light is off for fingers crossed it stays that way.Anyway the electrician said it was something to do with a wire causing high resistance.Does this sound right to you?Every time I turn the engine on keep expecting to see the light come back on

[C.Noble]

oops! missed this post today...

P0131 is a fault code relating to the Oxygen sensor, as are all codes starting p013x and relates to the first of the 2 sensors (before the cat) this particular code means for at least 40 seconds continuously, the sensor indicated a VERY weak air/fuel mixture or for 10 seconds continuously a weak air/fuel mixture, when this is detected, it should put the fault light on, and keep it on until it sees 4 "drive cycles" (that is 4 runs that start from cold and last long enough to reach normal operating temp) without fault, if it experiences the fault again within those 4 cycles, the counter is reset, and the light is left on.

In simple terms, if your light has been on for a week, and you use the car at least twice a day for at least 7-8 miles each time and the light has never gone off, that would suggest the ecu sees the fault at least once every two to three days, but this time can be longer if the car does nothing for a few days or the runs are too short.
If, now that your code has been erased, the fault light does not come on within the next two weeks, then the fault probably was caused by one of your old sensors.

But, if the light does come back on, then obviously they were not at fault, but at the very least, that is one possible cause probably ticked off.

P0131 basically means there is too much oxygen at the first oxygen sensor for too long, this can be caused by;

an exhaust leak around the sensor or the exhaust manifold gasket.
This would normally, but not always be audible to the driver, particlarly under full load.

Not enough fuel being delivered (blocked injectors/low fuel pressure,etc)
This would usually be apparent to the driver as a drop in performance, again especially under high load, although, if you are not guilty of driving like you stole it, you might never notice.

An air leak in the induction side
Unless REALLY bad, the driver probably wont notice this, but sometimes it will manifest in a bad/lumpy/high idle.

Faulty MAP (Manifold Absolute Pressure) sensor
this little sensor tells the ECU how much pressure there is in the inlet system, and is pretty much a direct indication of the load the engine is under, and therefore how much air is being consumed, if it is incorrect/lying, then the air/fuel ratio will be incorrect, and therefore the light will come on. As above, this may not be apparent to the driver, but may affect the idle.

I hope this helps... and that I havent bored the $%*$ off you all!

Lesson for today over ... next week, how to build a MINI race car in 7 days... then how to REBUILD a MINI race car in 6.

[Craig]

VERY interesting info there Craig - thanks for that.

[Burple]

Yip, Craig... what Craig says...
Top info!

(Arg!.. too.. many... Craigs... head... imploding!! )

[audrey]

Thanks for this Craig Really helpful hopefully the light will stay off this time keep you posted.At least I know now what these sensors are for.Anyway gonna go now you must be sick of all my questions