Why is my car revving so high on a cold start?
An engine running at excessively high RPMs during a cold start is typically caused by a vacuum leak, a faulty idle air control valve, or a stuck throttle body. This sudden surge prevents the vehicle from idling down normally and often triggers related fault codes like a P0420 catalytic converter error.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
- 1verifying if the gauge is simply testing the full range of motion on startup
- 2Restarting the vehicle immediately after it stalls or stumbles
- 3Checking the battery and fuel system
In their words
Unedited, most upvoted first, each linked to the thread it came from.
“I'm having an issue on Cold start only it stumbles and shakes the whole car like a horrible misfire and then after about 5 to 10 sec the rpm shoots up to normal and it runs perfect sometimes it will stall completely and I have to restart, if I turn it off and restart it turns on perfect it only does it on Cold start”source ↗
“I can drive as long as I want and it never does it again only after it sits overnight or after my shift 8 or 10 hours it does it again”source ↗
“Guy please help what could this possibly be and how much would it be to fix. it has a engine light for p0420 Cadillac converter”source ↗
“Im asking about the high rpm what could possibly be”source ↗
“HOW DO I fIX THIS HIGH RPM AT COLD START 8K CAN BE GOOD”source ↗
Where this came up
People with this problem also raised
- 5Why does my car lurch and shake when I accelerate at low RPMs?
- 2Why does my car take so long to start after sitting?
- 2Charging system voltage drops when revving engine
- 2Why does my car go into limp mode after warming up?
- 17Why does my car run terribly and stutter after a long drive?
- 8Why does my car engine cut out after driving for a while?