Low Coolant Light Issues

**Hair** · 09-23-2015

02 GP GT - Low Coolant Light came on and stayed on for about 6 months. Coolant was never low the whole time. I replaced the sensor with a new GM one. Light went of and all was well for a day or so. Now the light goes on and off from time to time. May stay on 5 minutes and might not come on for another 30 minutes, might come on 5 times during 30 minutes etc. Temperature hand holds steady at big mark between the 160 and 210 and coolant shows full always.

Could this be air in my system? When I changed out the sensor, I just stuck the new sensor in and added a little coolant back in the reservoir. I did not bleed it. I'm thinking air in the system would make the temperature fluctuate, but mine stays steady? Could air in the system cause this sensor light issue with no temperature fluctuation?... or maybe the new sensor is junk?

**idrivejunk** · 09-23-2015

Same issue with my 99 GT. Have not investigated mine yet, its a second car. But it almost HAS to be wiring. There must be a common wear spot in the harness, at least thats what I'd be checking first. I suppose it could be an instrument cluster issue too but that seems less likely. Maybe somebody has been through this and can fast forward. I have same symptoms but haven't changed the sensor yet.

**mguzzo** · 09-23-2015

if you are low on coolant and rev up, the pump can cavitate the radiator and cause the coolant level to drop. Sometimes people have described their lower rad hose collapsing because of this. If you take off the radiator cap and it's full up, rev the engine a few times and continue to burp it. air that collects near the cap *should* burp out thru the vent hose into the overflow and suck coolant back in, but for good measure make sure you're topped off.

**idrivejunk** · 09-23-2015

Originally Posted by mguzzo

if you are low on coolant and rev up, the pump can cavitate the radiator and cause the coolant level to drop. Sometimes people have described their lower rad hose collapsing because of this. If you take off the radiator cap and it's full up, rev the engine a few times and continue to burp it. air that collects near the cap *should* burp out thru the vent hose into the overflow and suck coolant back in, but for good measure make sure you're topped off.

This makes sense on mine, even though the radiator appears full. Theres a leak in the system drawing air in when the engine cools I'd bet. My light goes out sometimes when I'm on the gas, and usually doesn't come on unti the engine is warm.

**EHB** · 09-23-2015

when i first bought my car , the low coolant light was on. flushed the coolant , light stayed on. bought a $7 sensor from ebay with low expectations and installed it , the light went out. stayed off for a week. came back on for about 2 weeks , then went off again. hasn't been on for over 6 months now.

**markpa** · 09-23-2015

Could have Dex cool sludged up in the sensor hole.

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**99GT2dr** · 09-24-2015

Unplug it and light will never come back on. I think most people on this forum keep an eye on basic maintenance items often enough that the idiot light shouldn't be necessary.

**Scottydoggs** · 09-24-2015

also in the its unplugged club.

**Hair** · 09-25-2015

Well, one thing about it... seems that I'm not alone with this issue. I think I may try to bleed the system this weekend and see if that changes anything. I really hate to unplug it. I don't usually like doing things that way... but I'm not above it

**Scottydoggs** · 09-25-2015

bleeding wont fix it, its dirty, broken or your low on coolant, pick one.

**Hair** · 09-28-2015

Its not dirty, I just put a new radiator in and flushed everything about 4 months ago. Its all clean. Maybe "low coolant" was the answer. After I put the new switch in, I only added a little coolant to the reservoir. Because it seemed as if only a little ran out, but I really wasn't paying much attention at the time. I guess it was more than I though. Friday evening I took the radiator cap off and it was low... hardly low, but it was not full. The reservoir shows full, but the radiator was not up to the lid. Anyway, I started the car with the lid off and added maybe a quart of coolant to top it off. The light did not come on all weekend. Maybe that was it, I just should have actually opened the lid and added more coolant instead of what I tried.

I'm thinking that it was just barely right there at the level spot and so it was making the light flicker from time to time.

Whatever the case, the wife is back behind the wheel today, so if it doesn't act up with her driving, it will withstand anything.

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