Hi, I have a 2003 Dodge Ram 1500 5.9 liter gas, 4 door 4 wheel drive, 116,000 miles on it. My dummy gauge needle was only going a quarter of the way, it normally sits a hair below the halfway mark. My truck was throwing a code p1282 (engine too cold for too long). Replaced the thermostat (was installed correctly), t stat housing, coolant temperature sensor (located behind the alternator next the the heater core hose and t stat housing), flushed and put new coolant in. The dummy garage is now where it should be, but it’s still giving me the code. I only have a cheap basic diagnostic device (FIX’D) it scans and sends to your phone. Although everything looks right and the truck is running fine, the engine is still throwing the code and the FIX’D device is saying the engine coolant temperature is 181 F. I’ve run out of ideas at this point. I’ve had some say that is hot enough and others tell me it’s still running too cold. Any ideas? Thanks.

 

I think stock temp is 195...... what temp stat did you install?

 

195 T Stat

 

If it's only getting up to 180 or so then, its either a bad thermostat, a mis-boxed stat, or a bad sensor...... Wasn't a 'safety stat' by any chance was it?

 

It was a fail safe t stat . The last one was also. But this is the first time it’s thrown the engine running cold too long code. I was wondering if there could be another sensor other than the one I replaced next to the t stat housing that may need to be replaced that could be causing this? I was also wondering if the heater core has buildup in it (I do t get HOT air) could that cause a low flow issue resulting in a reduced coolant temperature?

 

Get rid of the fail safe stat. They are notoriously unreliable.

If you are getting good heat from your heater, it is not restricted.

Only one coolant temp sensor that I am aware of.

 

Definitely get rid of the aftermarket thermostat. I’ve replaced 5 in the past 2 years on my 02 -4.7 they are junk. Also blowing out coolant !!! Solution 👍. Replace the cap with a genuine Mopar. The aftermarket doesn’t seat down into the coolant tank deep enough 👍 1/4 inch too short. I bought 4 aftermarket until I learned my lesson

 

Sorry, I did not spell check my last post. I do NOT get HOT air. It’s just warm enough to thaw out frosted windows. On a 60 degree day the hottest it got was 67 degrees after driving for almost 40 minutes. I do NOT have any coolant leaks, it does NOT appear the heater core is leaking, this is why I was asking if you guys think there could be a blockage resulting in a low flow situation? Another thing I noticed is the air is a little warmer when the truck is sitting and idling, when driving its cools off drastically.

 

Bad thermostat will compromise heater performance, as will an air pocket in the heater core..... Serious problem with the 2nd gen trucks...... Getting all the air out of the system is a right pain in the keester.

 

Not too bad. I drain with the rear end jacked up and fill with the front end jacked up high or on ramps. First fill, then turn truck on leaving cap off, heater set to full hot, no need to run fan. Run for 20 min or so, letting air bubbles escape and filling as necessary. Once the thermostat opens, you can shut it down about 5 min after. To coax air out you can squeeze the bottom radiator hose but be careful of the fan blades when doing so.