Car Engine Revving in Park: Causes and Solutions

What Causes a Car Engine to Rev in Park?

When you put your car in park, the transmission is disconnected from the engine. This means that the engine is no longer driving the wheels, and the car should not move. However, in some cases, the engine may continue to rev even though the car is in park. This can be caused by several different factors, including:

Idle air control valve (IACV) problems: The IACV is responsible for controlling the amount of air that enters the engine at idle. If the IACV is malfunctioning, it can cause the engine to idle too high or low.
Vacuum leaks: A vacuum leak can cause the engine to run lean, which can also lead to high idle speeds.
Throttle position sensor (TPS) problems: The TPS tells the engine computer how much throttle is being applied. If the TPS is malfunctioning, it can cause the engine to idle too high or low.
Transmission problems: In some cases, a transmission problem can cause the engine to rev in park. For example, if the transmission fluid is low or dirty, it can cause the transmission to slip, which can lead to high idle speeds.

How to Fix a Car Engine Revving in Park

If your car engine is revving in park, there are several things you can do to fix the problem.

Check the idle air control valve (IACV): The IACV is located on the intake manifold. To check the IACV, remove the electrical connector from the valve and start the engine. If the idle speed drops, then the IACV is likely faulty.
Check for vacuum leaks: To check for vacuum leaks, use a smoke machine or a spray bottle with soapy water. Start the engine and let it idle. Then, spray the soapy water around the intake manifold, vacuum hoses, and other potential leak points. If you see bubbles forming, then you have found a leak.
Check the throttle position sensor (TPS): The TPS is located on the throttle body. To check the TPS, use a voltmeter to measure the voltage between the signal wire and the ground wire. The voltage should be between 0 and 5 volts at idle. If the voltage is not correct, then the TPS is likely faulty.
Have the transmission checked: If you suspect that the transmission is causing the engine to rev in park, then you should have it checked by a qualified mechanic.

Preventing Car Engine Revving in Park

There are several things you can do to prevent your car engine from revving in park.

Keep your car properly maintained: Regular maintenance can help to prevent problems that can lead to engine revving in park. This includes things like changing the oil and filter regularly, and checking the air filter and spark plugs.
Avoid driving in extreme conditions: Extreme cold or heat can put a strain on your car’s engine, which can lead to problems like engine revving in park. If possible, avoid driving in extreme conditions.

Conclusion

If your car engine is revving in park, it is important to identify and fix the problem as soon as possible. This will help to prevent further damage to your car and ensure that you are driving safely.