Fault code 42?

[AKS4]

My Engine Check light has come on in the last couple of days.

It initially only lit after restarting the engine when hot, but is now coming on most of the time. When it is not on (after turning the ignition on/off) the engine does not take the throttle properly and feels like the timing is too far advanced or retarded.

When the light is on - the engine runs ok but the performance is reduced (safe mode?)

I downloaded the Freescan software - and the ECU is reporting a code 42 fault (Electronic Spark Timing Circuit).

Has anyone seen this or had this problem before?

Is it likely to be a duff knock sensor?

thanks

Andrew

[alan]

I downloaded the Freescan software - and the ECU is reporting a code 42 fault (Electronic Spark Timing Circuit).

Has anyone seen this or had this problem before?

Is it likely to be a duff knock sensor?

thanks

Andrew

<{POST_SNAPBACK}>

It could be a duff knock sensor, but the other option is that the ignition module is not passing control to the ECU (this throws a code 42). At low RPM the ignition module controls the spark timing at high RPM its the ECU. You can check if the signal is working using a scope or multimeter. Have a look at the GM DIS ignition article on the following page:

http://www.autonerdz.com/clst.htm

Good luck

Alan

[AKS4]

Got it fixed! : )

I went through the test procedures from the service notes and the ECU looked to be at fault.

I had a look at the webside suggested by Alan - www.autonerdz.com which has an article on the Code 42 problem for American cars with the same GM ignition / ECU setup. They said that a subtle fault with the Coil unit (although testing OK) can sometimes be the culprit - and can't be ruled out without being replaced.

I sourced a new replacement direct from Lotus http://www.lotussurplusstocksale.co.uk for