My 2001 5.2 Ram has been giving me error code P1281 (engine cold too long) for several weeks. I've also noticed the truck will sometimes not idle from a cold start.

I figure it's either a faulty thermostat or temp sensor. Is there a way to determine if my thermostat is stuck open before I try to replace it? The cab heater blows warm air, although it will take about 5 minutes to warm up.

Thanks for any advice

 

If it is a 180 t-stat and it is under 20 deg. F you can get that code.

 

start it when its cold and hold the top rad hose when it gets close to temp...it will go from cold to hot all at once when the thermostat opens if it works...

 

I've got the stock thermostat, no mods to the engine.

After running the engine for about 5 minutes, I definitely felt the top rad hose heat up, but it was more gradual increase in temp than a sudden jump. I drove it for about 10 minutes and never saw the dash temp gauge go above 160F. The ambient air temp was about 52F.

I've also noticed I'm losing coolant somewhere. I topped off the reservoir (to the full line) about a week and a half ago, and to day the level was about halfway between "fill" and "full". Could be an unrelated slow leak, but could this be related to a low temp reading?

 

if the temp gauge moves at all, then the temp sensor is probably fine.

most likely its a failed t-stat. mine did that last year and i was able to change it w/o removing anything but the t-stat. leave the hose attached to the t-stat housing and remove the 2 bolts. use the hose to pull out the housing.

i don't think the coolant loss has anything to do with the t-stat failing. i'd say the water pump seal is leaking a little, possibly due to the cold weather. keep the coolant full, hope for the best, and wait for warmer weather.

 

If the ambient air temp was about 52F and it dosen't get to the 160 mark something is wrong.It might help to have more info about your truck(year model,engine,etc.)It being 52F outside I'd say your in the southwest or Fla. if in the U.S.A. at all.

 

Thanks, vaughan. I wasn't sure if the temp sensor used by the computer was the same one used by the dash gauge. That probably rules that out.

Sounds like I'll be replacing the tstat next weekend.

Thanks again, I appreciate the advice on this forum. I don't know much about cars and this has been helpful.

 

Just an update to bring this thread to conclusion: After installing new stock t-stat my error code has disappeared and I haven't had any idling problems in the week since I made the repair.

The DIY guides weren't kidding about grinding off the tab. It would be a real pain to get back in with the tab on.