low coolant

2002 GP GT 120,000 miles. I got a low coolant light after about 20 min. highway driving. It went out when I got off the highway. Is it possibly just low or is it more likely that I'm losing a head gasket? Had system flushed at 100k miles.

2002 GP GT 120,000 miles. I got a low coolant light after about 20 min. highway driving. It went out when I got off the highway. Is it possibly just low or is it more likely that I'm losing a head gasket? Had system flushed at 100k miles.

Let the engine cool down totally and check the radiator coolant level by removing tha radiator cap and looking in the filler neck. Don't count on the level in the reservoir. The coolant level sensor could just be clogged. It can be removed and cleaned. Located 3 inches below the radiator cap.

Also air could be causing it and just needs to be bled out since you got a flush.

An unexplained coolant leak or high consumption with no other driveability issues could be caused by a bad upper intake/lower intake or throttle body gasket. There is a GM TSB out on this problem for 2000 - 2003 Grand Prixs with VIN K Series II 3800.

The GM TSB number is #03-06-01-016 released in 2003.

Bob is correct (as usual). IF you're not actually losing coolant, sludge can get in the low coolant sensor causing it to trip the light. If you are losing coolant, and don't see it on the ground, the upper intake coolant passage near the EGR tube is probably eroded, leaking coolant into the engine. Get this resolved, as it can get worse to the point of filling a cylinder with coolant and hydrolocking the engine. This can cause bent connecting rods and severe engine damage.