What Causes High Idle Speed in Cold Weather?

[VanMelanie]

When starting a car in cold weather, the reasons for high idle speed are as follows: 1. High idle speed during startup is a normal phenomenon: a. The car requires higher RPM to allow the engine to reach normal operating conditions quickly. This necessitates a richer air-fuel mixture, leading to increased air intake and fuel injection, which results in higher RPM. b. Increased oil viscosity during cold starts: During a cold start, the idle stepper motor automatically adjusts to increase air intake, allowing more air to enter the cylinders. High idle speed is normal in this situation. 2. Excessive carbon buildup: Timely cleaning of the throttle body and idle speed control valve can generally resolve this issue.

[MacDonovan]

Actually, high idle speed in cold weather is quite common, mainly because the engine wants to warm up quickly to protect its components. The ECU detects the cold coolant through the temperature sensor and automatically increases the idle speed to 1500 RPM or higher, allowing the oil to circulate and lubricate faster, avoiding cold start wear or stalling risks. Once the temperature rises to the operating point, the speed gradually drops back to normal, such as around 800 RPM. If the idle speed remains high and doesn't come down, it might be due to a faulty sensor or carbon buildup in the throttle body, which needs to be checked and repaired. A temporarily high idle speed consumes a bit more fuel, but it's a normal phenomenon—no need to panic, just wait a few more minutes and it'll be fine.

[StTravis]

My car always idles high when starting in winter. Like during last week's cold snap when it was below zero, the RPM shot up to 1800 immediately after ignition, stabilized at 1200 after a few seconds, and then dropped to around 800 after another two minutes. The ECU is automatically adjusting to prevent engine stalling and ensure quick warm-up for cabin heating. If the idle speed remains too high, I've checked that it might be due to a dirty air filter or aging spark plugs - regular maintenance can prevent this. The high idle in cold weather is actually a protective mechanism to prevent engine cold-start damage, and it'll normalize after driving for a few minutes.

[DeLeila]

High idle speed in cold weather is normal due to ECU warm-up control, which increases RPM when detecting low temperatures. If the idle speed is abnormal, check whether the coolant temperature sensor is malfunctioning or if the throttle is clogged with carbon deposits. Regular maintenance such as cleaning carbon deposits and changing engine oil can prevent problems, and the high idle speed will decrease quickly.