Well my cam belt was done a few months ago but the car has been driving the same after as it was before, so I wouldn't have thought my timing was out. I'll have a look at the crank sensor though if you reckon it could be that.

Had a problem with a little fiat seicento the other day, multiple cylinder missfire.

All google searches said ecu, checked timing and it was 2 teeth out and the bottom pulley was out so the crank sensor couldn't get correct reading.

Sorted timing, sorted crank pulley but still same problem.

Found crank sensor had no bolt in it and was a couple mill off. Put bolt in and it has been mint ever since.

Yeah it would purely be for piece of mind but I'm not going to lose sleep over it or start spending loads of money on various parts just to sort it.

Thanks for your response, first person to do so out of 4 forums I've posted the problem on!

Thats exactly it, one person says ecu, someone says something else...
Then you get someone asking a question, it gets googled and it comes back to "oh its your ecu at fault"

I changed sensors, ecu, etc etc for weeks to cure my Gsi and like i say it was the pulley.

If your that concerned id suggest giving the engine a good look over and maybe try and source a cheap ecu to see if it does anything?
Thats for your piece of mind, ive already said id personally leave it

That's the thing, I've read so many conflicting things. I haven't really come across one definitive answer or clear response.

Even though the car has no problems it's still something I'd like to get to the bottom of and get rid of.

I was diagnosed with Quad Driver Module failure on my Gsi and googled it.. seeing the cause cant say i was pleased, But ignore most of it, my error was caused via the bottom pulley being worn.

Dont have much knowledge of the X14SZ, but if you say you have no problems, i wouldnt worry about it tbh

Hi Guys,

I drive a 1996 X14SZ Corsa B. I ran OP-COM the other day for the first time and have a couple of questions that hopefully some of you guys can answer for me.

The fault codes registered were:

P1640 - Quad Driver Module (QDM)
(00) - Not present

P1503 - Immobiliser Wrong Signal
(00) - Not present

P1502 - Immobiliser No Signal
(00) - Not present

I then cleared them and only the Quad Driver Module one came back, but it came back instantly.

I've had a quick look into this and I believe it could be either a dodgy bit in the ECU or perhaps the coilpack? Only difference with my car over ones from other threads I've come across is that my car is showing absolutely no ill symptoms whatsoever yet still has this fault code. No stalling, no struggling to start, no erratic idling, no lack of power etc.

In case it's relevant the car has the Multec/Simtec 56.5 ECU.

Anyone got any thoughts/suggestions?

Cheers, Robin.