P1281 Error 2002 Jeep Liberty

[brianjeep]

Hi all,
My 2002 Jeep Liberty has had the engine light going on and off recently and it keeps coming back with the P1281 (Engine is cold too long) error code. We had a new T-stat put in back in October 2017 by a local repair shop. The heater core was replace about a year before that along with the radiator. Since the engine light keeps going on then off I'm not convinced its the t-stat and wondering if it might be the sender for the tstat.

We've tried running the car and then touching the radiator hose compared to the heater core hose and the heater core hose heats up quicker than the radiator hose.

We've watched the temp gauge and it doesn't get passed the middle

We've timed the temp gauge getting up to the middle and it takes about 15 mins

We've checked the heat in the vehicle and it blows hot

We've checked the coolant level and it's fine

Any ideas?? Should we replace the t-stat?

 

[LibertyTC]

The thermostat could be stuck in the open position.
Only the Mopar thermostat should be used, what brand is in the Jeep now?

You must be registered for see images attach

By plugging into the OBD2 with a scan gauge or diagnostic reader, you can see the exact temp reported by the temp sensor. (fWT- Fahrenheit water temperature)

You must be registered for see images attach

 

[mrlavalamp]

Sounds like a stuck open thermostat to me.

the only confuser for me is when you say the two hoses are cold/hot.
It is hard to compare the temperature of each hose at any point in the start/warmup if I am not sure which hose you are talking about.

Typically if the thermostat is stuck open the hose feeding the heater core should heat up at the same time as the lower radiator (upper radaitor hose may take significantly longer, as well as the heater core return hose).

If thermostat is shut (as it should be when cold), the heater core still gets warm coolant from the engine, so the hose feeding the heater core will be warm but the lower radiator should be cool until the engine gets to temp.

But thermostats can have lots of problems outside simply stuck shut or open, which is why folks say go mopar or you will just end up going back to the parts store soon.

 

[tommudd]

I would start with MOPAR thermostat, others no matter from where do have issues

 

[brianjeep]

Thanks for the replies. I don't know what brand of t-stat was installed since it was done by my local repair shop, not by myself. It's just odd that the engine light comes on and off. If the t-stat is stuck open I would expect the light to stay on. Sounds like the only plan would be to get a new MOPAR t-stat and install.

 

[JasonJ]

Thanks for the replies. I don't know what brand of t-stat was installed since it was done by my local repair shop, not by myself. It's just odd that the engine light comes on and off. If the t-stat is stuck open I would expect the light to stay on. Sounds like the only plan would be to get a new MOPAR t-stat and install.

The MIL goes on and off because the condition is not persistent... sometimes it is present, other times not.. if it doesn't detect it after so many key cycles, it stores the code and turns the light off.

Considering that the t-stat is a thermal-mechanical part, the spring and valve could be periodically (but not always) sticking, or binding, causing your issue.

I think on these engines, it's also critical that the vent hole be positioned exactly a certain way as well... not just, toss it in there and go.