GM Service Manual Online
For 1990-2009 cars only

Running the Vehicle While Parked Automatic Transmission

It is better not to park with the engine running. But if you ever have to, here are some things to know.

Caution: Idling the engine with the climate control system off could allow dangerous exhaust into your vehicle. See the earlier caution under Engine Exhaust .

Also, idling in a closed-in place can let deadly carbon monoxide (CO) into your vehicle even if the climate control fan is at the highest setting. One place this can happen is a garage. Exhaust -- with CO -- can come in easily. NEVER park in a garage with the engine running.

Also see "If You Are Caught in a Blizzard" under Winter Driving .

Caution: It can be dangerous to get out of your vehicle if the shift lever is not fully in PARK (P) with the parking brake firmly set. Your vehicle can roll. Do not leave your vehicle when the engine is running unless you have to. If you have left the engine running, the vehicle can move suddenly. You or others could be injured. To be sure your vehicle will not move, even when you are on fairly level ground, always set the parking brake and move the shift lever to PARK (P).

Caution: If your vehicle has four-wheel drive, it will be free to roll -- even if the shift lever is in PARK (P) -- if the transfer case is in NEUTRAL. So be sure the transfer case is in a drive gear -- not in NEUTRAL. See Four-Wheel Drive .

Follow the proper steps to be sure your vehicle will not move. See Shifting Into Park .

If you are pulling a trailer, see Towing a Trailer .