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Engine light at the trackday


New member
12 May 2021
Hi everyone.
Last week went to track day at Cadwell Park. All was going pretty well until Engine light came on. It happened couple times over morning session always at the end of the straight and it disappears after few corners. But after lunch engine light came on and cut the power. So limped back to parking area and let it cool down, checked connections to coils and other components that I could reach and all secured but fault still there. Drove on the street, seems all OK but decided to pack up for the day. At home scanned with OBD reader and these faults came on:

P0638 Throttle actuator control range/performance bank 1
P2122 Throttle adjusting unit potentiometer 1
P2127 Throttle adjusting unit potentiometer 2
P0830 Clutch switch input circuit
P0300 Misfiring, checksum error
P0301 Misfiring, cylinder 1

Cleared the faults and drove car for a few days on street, all good. No faults.
Who caused all these Faults?
Would like to book another track day in a month or two but would like to find the cause. That wasn't my first track day but never had any faults before.

You seem to have a couple of things going on there and to me both are heat related ..

A single misfire .. coils can break down when they get hot giving a weaker spark than what's needed ..

I would say replace the coil And the spark plug on No,1 cylinder only .. don't do all 6 as we are fault finding and its not warranted for this fault regardless .

A misfire will trigger an eml ..

general rule of thumb .. eml light will come on if its emissions related .. basically it's down to save the planet stuff .. if a cat is defective .. eml on , lambda sensor .. eml on ..

A disconnected knock sensor .. fault code only and no eml .. it is a fault .. it needs to be fixed but its not emissions related so you get no indication its faulty .. fuel pump .. i could go on ..

Stupid in my book as a fault with the engine should bring on an EML regardless .. sigh ..

Sorry i'm waffleing .. some things annoy me is all .

Ok the throttle .. technically no eml but if the engine control unit cant see a usable signal from the throttle ( 2 potentiometers as a redundancy system ) then it might if both went ..

The car though .. you would have no throttle .. you didn't mention that ..

For me .. my car .. i would change coil and plug as mentioned ( cheapest first option as well ) , clear codes then another track day or a seriously hard drive to simulate a track day and see what you get ... not going to condone that on public roads though :)

Clutch switch fault .. im ignoring that for now as i dont feel its relevant to this fault .
Thank you very much deMort.

Will do coil and spark plug for cylinder 1.

Had a day off today so checked clutch switch and it is just dangling there. Clips broken. Also took air pipe to throttle body and cleaned it. It wasn't that bad. Bit oily inside but that probably from AOS. Operated Throttle body with pedal and it is opening fully. Felt nice and smooth than operated with fingers.

Will book an evening session next time to test, and will take OBD reader this time. Probably would be wise to take couple coils as a spare. But what's for future.

Thank you deMort, will let you know if this sorts out the issue.

So, replaced spark plug and coil and had a good drive. All good, no EML.

Not much room for Cylinder 1 coil, and spark plug socket got stuck inside. But managed to get wiggled out with extension.

Will book a track day evening next month :thumbs:

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