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High idle
Posted: Thu Dec 04, 2025 7:05 pm
by Jack_555
Hi all my car usually idles at 650 however when i turn the heater on it goes up to 1000 but will not go back down even with the heater off. It will still idle at 1000 a week later after many times restarting the engine? Any ideas
Re: High idle
Posted: Sun Dec 07, 2025 7:08 pm
by RUM4MO
Hi, I'd think that you would get better "coverage" if you posted into the right forum main area.
Anyway, this might be a failing battery issue and the engine RPM is being kept "up" to counter that issue.
Any time I've been waiting at traffic light in cold weather, with my wife's 2015 1.2TSI 110PS 6MT, the idle has been high especially if I've driven "quietly/smoothly" for a few miles prior to that, I bought and fitted a cheap plug in 12V DVM into the 12V Power socket, having that to look at can explain a few things. In certain circumstances you (I) can end up with the car having harvested the stored energy in the battery by driving smoothly, so it doesn't, if allowed, auto stop, I can see this from the real time voltage at this 12V Power socket.
In fact, today I have been re-informing myself with how to read the battery statistics and how to re-code the battery, I've got a replacement Bosch AGM battery waiting to get fitted, didn't happen today due to F1 race and laziness, maybe a job for tomorrow temperature permitting!