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Engine Coolant Gauge

6K views 12 replies 6 participants last post by  plano_doug 
#1 ·
So I posted a thread on this a while back.

Well my coolant gauge used to malfunction intermittently. It would sometimes go out while driving. Other times it wouldn't work from starting the car. Well it stopped causing problems for a few months.

Now the problem has come back around. I noticed it would drop to 0 or "100 degrees" when I would be driving and changing the air flow (head, feet, defrost, etc) Well now today the gauge has yet to come on at all. The fans are blowing at full blast. AC works and heat works.

Some say it's the coolant temp. sensor. Some say it's the thermostat itself. I was hoping someone would be able to tell me exactly the cause before I start chasing ghosts with the little money I have.

Also I have yet to have a check engine light come on during this problem.
 
#2 ·
I was hoping someone would be able to tell me exactly the cause before I start chasing ghosts with the little money I have.
If someone could do that they wouln't be on a G6 forum, LOL.

Could be bad sensor, intermittent wiring connector somewhere, issue in the gauge or cluster, etc. A faulty thermostat would give you no hot heat (if stuck open) or overheat the engine (if stuck closed).
 
#13 ·
Could be bad sensor, intermittent wiring connector somewhere...
A wiring issue gets my vote.

Since the fans are on _and_ the gauge is wonky, that indicates the problem is farther upstream, towards the sensor.

I would inspect the wires near the temp sensor connector. Pull them from the loom if necessary. Look for either a broken or chafed spot on the wires. Look for a limp spot as well (indicating the wire is broken inside the insulation). Look closely at the wires where they go into the connector.

It may be necessary to remove several feet of wiring from the loom looking for the bad spot. Perhaps there's a heat-damaged spot from the harness being routed too close to the exhaust.

As for dielectric grease, keep in mind, it's an insulator, not a conductor. So it should only be applied where the rubber seals join the plastic connector housings, but not applied directly to the contacts in the connector.

HTH.

Doug

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#4 ·
I wish you the best of luck... I have a 07 Malibu that has similar problems. Ive changed coolant temp sensor twice and thermostat twice, until I found that disconnecting the battery for about ten seconds gets everything going again. which ruled out the thermostat being stuck open. So the next thing I did was clean out the connector to the sensor with a small wire brush and throw some die electric grease in there. although I'm not driving it anymore, I haven't heard of any problems for a few months now.
 
#5 ·
I have the same problem with my 09 G6 convertible. The fault code is P0128 when the car thinks it isn't warming up fast enough, so GM shuts off the gage and runs the fans full blast. I think the AC is also disabled. I have a bluetooth enabled OBD2 reader which can log data to my android phone. The ECT sensor seems to be fine, as does the thermostat, based on the temperature data. I've been resetting the fault code when it happens (about every few weeks). I would like to know if anyone found a REAL cause/solution for the problem. I don't want to replace the thermostat and/or the ECT sensor just to be stuck with the same problem and an unnecessary repair bill.
 
#7 ·
I would like to know if anyone found a REAL cause/solution for the problem. I don't want to replace the thermostat and/or the ECT sensor just to be stuck with the same problem and an unnecessary repair bill.
There isn't such thing as "the problem". It could be many different faults. In my case it was a bad thermostat. Stuck open. Your fault may be different. A good mechanic should be able to look at all the symptoms and diagnose it correctly.
 
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