Trouble starting after warm. No crank/no start

aod.is200 · July 19, 2022

I've had this issue lately where my IS250 will not crank after being run for about 30 minutes or more and while the engine is still warm. The car will eventually start and crank with no issue after another 30-60 minute wait and will crank and start in the morning with no issue.

I'm a bit stuck about where to go next to diagnose the issue. The key fob Battery is fine and lights up green when pressing my foot on the brake. There are no fault codes that have been detected and no engine light when attempting to start.

Could anyone help any further with this?

I've attached a video as an example.

Thank you

NemesisUK · July 19, 2022

CPS is always the prime suspect for problems with warm starts.

aod.is200 · July 19, 2022

5 minutes ago, NemesisUK said:

CPS is always the prime suspect for problems with warm starts.

It's one of the things that's crossed my mind - however, wouldn't this at least leave a DTC?

At least I would have thought so?

NemesisUK · July 19, 2022

It only 'fails' when warm/hot, once it's cooled down it's ok.

aod.is200 · September 11, 2022

Trying to bump this topic again. Yesterday I changed the crank position sensor, a bit of a nightmare considering it's right under the AC compressor, but got there in the end. On my drive back from work and getting the engine warm again I turned off and attempted to start again.

Same issue, no crank while warm. I'm beginning to think this may be more starter motor related considering all other signs of life seem to be there - fuel pump is whirring etc.

Has anyone here come across a similar issue? Only other thing I can think of is looking at the grounds for a loose connection.

Any help would be greatly appreciated

aod.is200 · October 1, 2022

Just a quick update, symptoms seem to have gotten worse and the temperature needle doesn't even have to be half way anymore, it does it around 1/4 of the way up the gauge now.

My only guess that there's trouble with the starter motor getting hot and not functioning. I'll keep you all updated

ColinBarber · October 1, 2022

Check the starter relay first, if that is functioning then the starter solenoid could be at fault.

aod.is200 · October 26, 2022

Hey guys, just wanted to update anyone stumbling across the same issue I had. Turns out the problem was starter motor related, however it didn't need replacing. I had bought a new starter ready to change but it had turned up a bit longer than expected, about 1.5cm longer than the OEM part - because of this it wouldn't fit past the engine mount in order to fit it.

However, upon removing the original starter motor I had found the plug had actually come off its wire, so when it was disconnected it just fell straight off. I believe that it must have been loose for some time and as the engine got hot it was enough to expand things ever so slightly so it wasn't making contact with the starter anymore.

Anyway, I've reattached the plug to the wire and made sure it's no longer loose and reinstalled the old starter motor and it seems to be working a charm now. Over the last 5 days it's started every time regardless of engine temperature.

Hopefully this will help someone if they're having a similar issue, but it doesn't look like something that would be a common issue.

Thank you for giving your opinions and helping out guys! Really appreciate the help!