Thread: Engine fault light - Crankshaft Position Sensor

voltages will/ can cause this. i recently had a v6 petrol d3 with a faulty/ failing starter solenoid contact set, almost every time this faulted, ( went click and no start), the 'f' message and crank sensor fault appeared.

after starter repaired, resulting in minimal volt drop during cranking etc this problem seems to have disappeared.

jc

This post will not be of much help I fear.

I do like the idea of a voltage problem - most likely low voltage rather than a spike.

I say that as to me, it seems most of the warning lights are on problems seem to be what I would call false warnings and serve only to lead owners on endless wild goose chases.

A brake light switch that is failing shows not as no brake lights but as Cruise Control not Available or Transmission Fault or any number of other false messages.

In the case of a faulty brake light switch, the crank sensor does not seem to be one of them or any error code related to crank sensors.

An engine fault light usually means something is wrong with the emission system rather than some true mechanical problem. Since emission system warnings are all sensors, then a faulty sensor or the wiring to the sensors could be a problem. I know one guy discovered that hungry mice had been dining on his wiring under the engine cover. He determined that only after he removed the plastic engine cover.

Given that most sensors these days are some kind of transistorized resistor, if follows that a low voltage condition could trigger some kind of warning.

I guess what I would first do is every night for a couple of weeks when I park the 3, I would put a trickle charger on the battery.

I have a CTEK charger that I routinely use and that seems to keep the crazy error codes away. It can take a week of nights to get even a good battery up to a full charge state. Once the battery is fully charged, (something that it appears will never happen no matter how much you drive), the engine warning light may stop coming on.

I like the "charge the battery" as a first try solution as it is easy, costs nothing, and can do no harm.

Thanks Justinc and BByer - you were spot on with Voltage being the problem but it was not the battery - turns out the negative terminal on the battery had been over tightened at some stage and was no longer clamping fully. When loaded during starting it resulted in a volt drop because the "loose" joint could not deliver the current required. After it had started the "loose" connection could deliver enough for the cars electronics to run Ok. Finally solved - Touch wood.

Glad I asked you guys first and didn't spend the $$ going down the whole gearbox off route as they suggested because I would still have had the problem as well as a empty wallet.