Check engine light - accelerator?

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Corsa 1.4 auto (2015). The yellow light started glowing intermittently and I suspected E10 petrol. So eventually, after two limp home episodes, I took it to the local Vauxhall garage. They diagnosed an accelerator pedal/throttle issue and, £400 quid later, have replaced both. I'm just curious to know the engineering explanation of all this. The bloke at the garage was very helpful and explained that the diagnostic check had flagged this but didn't go into details. Can anyone give me a non-technical explanation?
 
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They diagnosed an accelerator pedal/throttle issue
I had a similar problem with a Corsa and a similar diagnosis. Replacing the pedal assembly alone (thankfully, as the throttle body part was a much more expensive item) cured it.
I did an autopsy on the pedal and found that it has two potentiometers working mechanically in parallel but electrically separately (presumably to provide comparative readings for error sensing). Each potentiometer has a spring-finger wiper moving over a conductive track. The poor quality conductive tracks had both worn through at the low throttle end, so the pots were giving inconsistent readings, which obviously upset the ECU.
Here's what the worn tracks look like :-
Resistive-tracks.jpg

(The yellow numbers are what I added to the pic for reference.)
 
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