My 2018 Honda Civic shakes violently when idling on cold mornings. RPMs fluctuate between 500 - 1000. No check engine light. Changed spark plugs last month but issue persists. Could it be a vacuum leak or bad oxygen sensor?
Yes, a faulty O2 sensor can cause this issue. It helps regulate the air-fuel mixture. If it's not working properly in cold conditions, the engine may run too rich or lean, resulting in rough idling and vibrations.
If it’s the O2 sensor, why would it only happen when the engine is cold? Wouldn’t it affect performance all the time?