TjbRubi

I have 08 unlimited auto. 38,000 miles. 35" toyos and 5.13 gears.

2 weeks ago my check engine light came on, and then went away. Since then the light is on about 75% of the time, and the radiator fan runs constant. The temp gauge stays at the midline. About 25% of the time a throttle sensor light comes on too. Jeep seems to be running fine.

Took it to the dealer Tuesday. They first said it was a bad thermostat, and replaced it, however that did not fix the problem. They then messed with it the whole day and said they could not figure out what the problem was, but it might be the water pump. They said there was a large difference in the temp from the "top compared to the bottom."

Took the jeep to different dealer closer to my work on Wed and they said the problem was the radiator was clogged and it needed to be replaced. They ordered the parts, replaced the radiator and did a coolant flush today. Picked up jeep this afternoon and everything seemed fine.

Started Jeep tonight, and check engine light, throttle light, and radiator fan started blowing immediately. Anyone else have similar issues or ideas? Can't wait to hear what the dealership says tommorrow!

ronjenx

What are the codes it throws?

1. To check your Jeep JK Wrangler’s DTC codes, simply insert your key into the ignition, turn it to the ‘ON’ position but do not start the engine. Then, push the key into the ignition cylinder and while holding it in, turn it to the ‘OFF’ position and then back to the ‘ON’ position (3) times straight making sure to end with it in the ‘ON’ position. It is important to keep pushing in on the key to prevent it from catching at the different positions along the way.
2. If you do step #1 correctly, all your dash lights will illuminate and your odometer will show up as a series of (6) dashes as shown in the pic to the left. If your Jeep JK Wrangler has any logged in any DTC’s, they will be displayed soon after the dashes appear. Write down the DTC(s) and check it/them against the list below to find out what they mean.
3. If your Jeep JK Wrangler has not logged in any DTC’s, the dashes on your odometer will be followed by the message ‘-done-’. Turn your key to the ‘OFF’ position and you will in fact be done.

cgwelder

I had the same problem with my Cherokee, but the fan would keep running AFTER I shut the jeep off and would run until the battery died.... It ended up being an $8 fan relay... Pull the fan relay from the fuse block and see if the lights/fan come on when you start the jeep.

TjbRubi

Thanks, one code showed up: p2181

Greysand

Did you by chance mix the green antifreeze with the orange? Mixing this new stuff can sometimes cause it to gum, cloud or form a clog. If the system is clogged somewhere you will see a temp difference from top to bottom.

See if they will pull the freeze plugs and flush the system under as much pressure as they can get into it.

TjbRubi

no mixing of green and orange antifreeze. It's weird because the temp gauge has not gone up, could be something electrical causing poor communication? The radiator fan will run full blast

ronjenx

Could be the fan is defaulting on because the temp data is not reliable.


P2181-COOLING SYSTEM PERFORMANCE

Set Condition:
PCM recognizes that the ECT has failed its self coherence test. The coolant temp should only change at a certain rate, if this rate is too slow or too fast this fault will set. Two trip fault. Three good trips to clear MIL. The MIL and ETC light will illuminate.


Possible Causes

LOW COOLANT LEVEL

(K2) ECT SIGNAL CIRCUIT SHORTED TO VOLTAGE

(K2) ECT SIGNAL CIRCUIT OPEN

(K900) SENSOR GROUND CIRCUIT OPEN

(K2) ECT SIGNAL CIRCUIT SHORTED TO GROUND

(K2) ECT SIGNAL CIRCUIT SHORTED TO THE (K900) SENSOR GROUND CIRCUIT

THERMOSTAT

ECT SENSOR

POWERTRAIN CONTROL MODULE (PCM)

TjbRubi

Thanks for your help ronjenx! I will copy the above and bring it to the dealership tomorrow

ronjenx

Each of the possible causes has a detailed procedure to see if it is the cause. The dealer should be taking those in order and performing the tests to find which one is the cause. If the thermostat and radiator have been replaced, it sounds like they are not reading their own tech data.

sixt7gt350

I had similar symptoms, except my temp gauge would jump from dead center to either flat nothing or full hot.
Same electronic throttle light.
The fan comes on full blast since it assumes the worst and is trying to keep things from cooking.

It was my coolant temp sensor.
'08 Unlimited auto.

P2181 gets thrown because it doesn't like the temp reading varying too much at once.
Once the temp sensor was replaced, all was good.

The first night it happened, it went from center to full hot in a matter of seconds. I freaked out and replaced the thermostat, concerned I actually had a thermostat problem and didn't want to cook the engine.

Good luck getting the part. They had to order mine.