immobiliser fault

[bill196510]

is there any way of disabling it.or another fix

[wheeler]

Really need a bit more details on the fault, might be a simple fix. I reckon more than half the posts on here about possible immobiliser problems turn out to be nothing to do with the immobiliser at all. Unless it actually says immobiliser fault on the display and/or the key symbol lighting up on the dash & not going out its unlikely to be an immobiliser related issue.
As far as disabling it goes, as far as I'm aware the only way to do it is to open the ECU, de solder a certain chip & re write it without the immobiliser function. It's not something I know too much about but it would require a soldering station, an EPROM programmer & software for removing the immo function. You can send your ECU off to have this don't but its not that cheap.

[bill196510]

says immobiliser fault on display

[spider]

Lexia should give a more detailed diagnosis, well should state the cause I'd expect. It may be something as trivial as the transponder aerial having one of its moments.

@Wheeler, I seem to think some are EEPROM's now so desoldering is not needed although as you say its not a trivial thing to do anyway as you'd have to download and remove it from the code then upload it back, and hope that nothing broke in the mean time. Correct me if I'm wrong though please as I'm just merely curious about the later models and this function.

[wheeler]

As i said i dont know a lot about this sort of thing but do you mean doing it via the obd socket or do you mean reading & writing the chip while it is still on the ECU ? If you mean via obd then i do belive some makes & models of car can be done this way but not PSA stuff as far as i know. If you mean reading the chip in place then yes this can be done but according to the guys that do this stuff its a lot more risky & higher chance of bricking the ECU.

[wheeler]

says immobiliser fault on display

Will it start at all or is it an intermittant fault ? Have you tried the spare key ?

[m300td]

have you tryed the spare key just to rule out the transponder in the key another fault is the transponer inductive coil which fits around the inginition switch barrel i have known these to go open circuit check for continuity
malc