E46 Electrical gremlins

[Smartass]

Hi guys,

A few weeks ago the outside temp sensor on my E46 330i went haywire and started to give a wide range of false readings, usually either plus 50 or minus 40 degrees. Last week it started to change it's mind virtually every second, usually reading a very large negative number and beeping loudly each time it changed (presumably the frost warning kicking in).

I was going to leave it until the next service but tonight the traction control light came on and won't cancel. I don't know much about the technology in the car, could I be looking at a new ECU? Happily I think I have a couple of months' warranty left on the car...

[TheEnd]

I'd say you have 2 separate problems, the temp indicator is most likely a poor connection or broken wires, which intermittantly give 0v, which relates to something like -37'.

The traction light probably won't be as much fun. If it was a wheel sensor, the speedo and ABS would also play up, so it's something more specific to the actual traction system itself.

[Neil.D]

The outside temp sensor is under the front bumper - drivers side I think. If they get wet through or a hard knock they can break giving these false readings. Have a look and a feel under there - it may be hanging off or snapped. it is a couple of inches underneath and looks like half a cotton bud.
They are not expensive to replace which would probably be your first option.

regarding the TC light - one of your ABS sensors may be broken, these too dont like deep water or puddles, or may just be covered in shiet. Give them a good hoseing off/pressure washering to start.
Worst case would be identifying the individual sensor that is broken, or a new ABS unit - which would be worse still.

Neil.D

[Neil.D]

...oh, no it doubt with some certainty that you need a new ECU.