[BH1]

My water temp gage drops to the floor, the cooling fans come on and active rev match turns off. Turn off the car and the fans remain running until I disconnect the battery. I thought it was the thermostat, so I decided it’s a quick fix and took it to the dealership the next day.

Fans come on as soon as I start it in the morning and the temp gage remains on the floor. I have a p3 gage and the coolant temp is great, so is the oil temp. On the 4 mile trip to the dealer, the the temp gage comes back online and the fans go off, but an engine light comes on.

They replace the thermostat and everything seems ok for 4 days. Then same thing happens again today. Coolant temp is good, oil temp is good. Thoughts?

[Mark114]

It sounds like a problem with the wiring harness to the temperature sensor. Maybe a loose connector or the harness has an intermittent short someplace from rubbing. Check the connection to the temperature sensor and the wiring harnesses near the fuse box in the engine compartment.

[BH1]

Thanks Mark114. I’ll give it a look.

[Eldi Z]

Originally Posted by Mark114

It sounds like a problem with the wiring harness to the temperature sensor. Maybe a loose connector or the harness has an intermittent short someplace from rubbing. Check the connection to the temperature sensor and the wiring harnesses near the fuse box in the engine compartment.

My problem was exactly this! Bad electrical connection.

Wiring harness to the Temp sensor (rectangular connector): in my case, it happened to be one of inside metal connects "tweezers" that lock onto the sensor's connects: One of them loosened up and gave an intermittent signal to the ECM.
Fix was simple - took long nose pliers and carefully pressed together the connects to form a better lock on the sensor's connects.

Such false signal triggers "cooling safe mode", which results in the following phenomena:

1.) Rad. Fan on full blast all the time (and continues to work for ~ 8 mins. even after shutting off the ignition).
2.) Cluster's temp. gauge pegged to Min.
3.) AC compressor will not engage = no more Aircon.
4.) CEL fault lights up (can be erased with Diagnostics tool)

[BH1]

Thanks Eldi Z!!

[GTIanZ28]

I’m having this exact same issue.

Mine is a V6 though. How do I figure out which of the 10 or so connectors is the temperature sensor?

I fiddled with all of them yesterday to make sure that they were properly seated. This has been an intermittent issue, but now it seems stuck in this fan on 100% mode.

I almost bought a new thermostat/housing. Know how to do something that simple. Was also considering replacing relays.

But, I’d like to try this connector fix first.

Edit: I have a diagnostic tool to delete codes as well.

Edit #2: found a pretty good post with multiple people having the same issues with both V6 and V8’s. They claim that it’s 2 possible things. Bad temp sensor or bad thermostat.
https://www.cargurus.com/Cars/Discus...59580_ds984204

[Shadyredeyes]

Mine did the same thing. Had a leak at the thermostat housing. Replaced that and the thermostat. Bam. Problem gone.