Random Starting Failure - Help
 

I have a 2001 S with 54k under its belt. Pampered car that’s never missed a service. Randomly, it failures to start. The starter motor spins with great vigour buts there’s no spark. I’ve replaced plugs, all coils, crank sensor and fuel filter. My local specialist has now said it might be that modern fuel is the problem and I should try reddex!
Has anyone else had this issue?

We have seen this when the crank position sensor is going south; the immobilizer in these cars is programmed to shut off the fuel and ignition if the immobilizer does not see the engine turning over, which it gets as a signal from the CPS. This could be a harness problem between the sensor and the immobilizer, causing the intermittent issue.

Thanks. That makes a lot of sense 👍

I have had 2 bad CPCs. One on an engine I bought, engine cranked but no start... replaced CPS... started.
The other on a different car was intermittent... it would start fine when cold and run till I shut it off... but would not start when hot. An hour later it would start. Replaced the CPS... problem solved.

One of the bigger problems we see all the time is cheap aftermarket CPS that either don't work well or even at all. In the end, the best method to test CPS units is with a scope, which quickly shows the problem; cheap parts are often garbage.