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Coolant Sensor Question

m42duster

NAXJA Forum User
Location
Ohio
If the coolant sensor is going bad will it cause the engine to bog down when it triggers the check engine light. I am not exactly certain it is actually overheating or the sensor is misbehaving. Anyhow, I have a sensor ordered and will install Tuesday. I remain curious if it could cause this behavior.

Might be a stupid question, if so, I have plenty more of them.
 
BASICS--year/engine?
 
Ok, so you got a code and you are replacing the CTS based on that?
 
Ok, so you got a code and you are replacing the CTS based on that?

I got the sensor for $17.00 so I figured I'd just swap it just for peace of mind. This is my ex-wife's jeep and for the second time it has spiked the guage and displayed the "check guages" indicator. It's weird, but both times this has happened, she was on the phone with me at the very instance it occurred. Just as I told her to pull over and shut the engine down, she said the temp guage was back under 210. She's not the type to listen to reason and will just keep on going. Both times she was doing 50-55 mph on the highway. Also, both times she said the engine was doggy and smoothed out quickly when the temp went down.

She said she could hear the electric fan running (AC was on) It's strange that it seemed to just spike momentarily and then rapidly drop to a safe level (30 secs or less). So the question... can a fualty sensor send data that would make the engine run crappy then smooth out when it registers a safe temp. I hate to keep driving to her house (48 miles) while her moronic boyfriend peeps out the window. Since my son rides in the Jeep, I tolerate such things.
 
Yeah, you are a good man, Charlie Brown!

Ok, I wouldn't expect a quick spike and return from a variable resistor, and that is really all the CTS is.

Sounds more like a harness/PCM issue.

Has she had any issues with the cooling system that you are aware of? Could it be losing coolant and getting air pockets?
 
No coolant loss so far. I showed her the line on the bottle to compare and she says it stays there. I will check for air. She bought the rig about a month ago and some old receipts show it was looked at by Tuffy's for a overheating problem. It showed they replaced the water pump, thermostat and flushed the radiator. This was around a year ago.

After the first spike I replaced the fan clutch, flushed the radiator, new stat and rad cap. The coolant looked very clean with very little sediment. I figure this Wednesday I'll change the sensor and test the coolant for combustion gases and go from there.

I'm beginning to think the PO had some issues left unmentioned.

Thanks for your replies.
 
Don't forget to renew the grounds, could be that simple of a problem.
 
To answer the question, yes it can cause the problem you're seeing. Most of these things use variable resistance on a grounded circuit, with open circuit (no continuity) for zero/null and full ground (full continuity) being 100% signal. If the sensor or circuit shorts out then the computer will see maximum signal strength. The OBDII system should store a code for this event, too.
 
I got the sensor for $17.00 so I figured I'd just swap it just for peace of mind. This is my ex-wife's jeep and for the second time it has spiked the guage and displayed the "check guages" indicator. It's weird, but both times this has happened, she was on the phone with me at the very instance it occurred. Just as I told her to pull over and shut the engine down, she said the temp guage was back under 210. She's not the type to listen to reason and will just keep on going. Both times she was doing 50-55 mph on the highway. Also, both times she said the engine was doggy and smoothed out quickly when the temp went down.

She said she could hear the electric fan running (AC was on) It's strange that it seemed to just spike momentarily and then rapidly drop to a safe level (30 secs or less). So the question... can a fualty sensor send data that would make the engine run crappy then smooth out when it registers a safe temp. I hate to keep driving to her house (48 miles) while her moronic boyfriend peeps out the window. Since my son rides in the Jeep, I tolerate such things.

Since the cap, thermostat, water pump, fan clutch were replaced and cooling system has been flushed and void of sediment; there isn't too much more..
Just wondering if the water pump suction hose is collapsing at highwya speeds causing the pump to cavitate and engine to over heat due to lack of coolant flow.
On the older Jeeps the manufacturer would install a stainless coil spring inside the hose to stop the hose from collapsing. Might want to check the hose to see if it is an inferior grade hose or it has become soft which would allow the hose to collapse.
 
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