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2014 WK2 Overland
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padgett, here's what I have to go on regarding condtions for the P0128 to set.

When monitored: With the engine running, ambient temperature between 8C(17.6F) & 50C(122F), startup coolant temperature less than 50C(122F) and average vehicle speed greater than 16KPH(10MPH), untill the vehicle untill coolant temperature reaches 85C(185F).

Set conditions: The PCM detects that the actual coolant temperature falls too far below the predicted engine coolant temperature and the predicted engine coolant temperature reaches the predicted target value before the actual coolant temperature reached the actual coolant temperature target value. Two trip fault. Three good trips to turn off MIL.

Possible causes: The top two are most common.
-Low coolant
-Thermostat open
-Temperature sensor
-Signal circuit open
-Signal ground circuit open
-Signal circuit shorted to ground
-Signal circuit shorted to the (K900), (G931) sensor ground circuit
-Powertrain control module (PCM)
 

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Discussion Starter · #22 ·
Tourque is a great app, not sure how much it would have helped since mine was so random coming on and then I believe would stay on for X (maybe 100 or 50) amount of miles and then the check engine light would clear. 2-5 days later it was back on.
 

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Discussion Starter · #23 ·
after almost 2 weeks the P0128 code has not returned (knocking sound on wood) so hopefully it is resolved with the t-stat change
 

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Good deal. Usually when that code starts to appear, the thermostat will stick open intermittently untill eventually it will remain stuck open.
 

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2011 Jeep WK2 LarX
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Does anyone have the diagram of where the ECT and/or Thermostat is located? I just got the P0128 today, planning to tackle it this weekend.
 

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Well can eliminate most of the faults if you have a reading (forgot to mention that you should be able to get a coolant temp readout in the EVIC.)

What Torque reads is what the engine thinks the temp is. Personally would be surprised if the fault sets above 82C/180F.

Nice thing about the Torque Pro app is that it can create a log file of parameters you select. Can go home, load on PC, & see when the MIL/CES light comes on and check the surrounding parameters (e.g. coolant temp).

I keep mine running on a dash tablet whenever in the car. Still trying to find the parameter for trans temp though - can dsplay with EVIC so know it is on the bus. Anyone know ?
 

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I finally picked up my thermostat and coolant today, was planning on doing the job tomorrow. Thermostat looks good, but did I get the wrong coolant? Not the same part number listed on wk2jeeps. I told them for the same vehicle as the thermostat, and even asked if it was HOAT, and he said yes.
Anybody know if this coolant is okay? It's OVU01524-AB
 

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I finally picked up my thermostat and coolant today, was planning on doing the job tomorrow. Thermostat looks good, but did I get the wrong coolant? Not the same part number listed on wk2jeeps. I told them for the same vehicle as the thermostat, and even asked if it was HOAT, and he said yes.

Anybody know if this coolant is okay? It's OVU01524-AB



Is it red color or green or what
 

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Well that was easy:) One hour and 5 minutes including letting it idle to operating temp. Upper rad hose shot from 20 deg celcius to 50 when the engine temp hit 96, so seems to be working. Followed Ratchet's instructions regarding refilling and worked great! Going to check coolant level in a few hours.
Now some pics:



 
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Discussion Starter · #31 ·
great work, I did not take any pics after I broke lower bolt
 

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On a related note, I don't have a code and I've only had my '12 JGC for 2 days but I noticed today the the gauge never gets to the 12 o'clock position, even after an hour on the road, its actually about half way to pointing straight up. My recent history is in German cars where normal temp is at 12. Is this low temp normal for our cars?
 

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Discussion Starter · #33 ·
mine was about 1/4 to 1/3 before i switched tstat and now is maybe 1/3. the only time i see 1/2 is in traffic and then the fan comes on
 

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Well that was easy:) One hour and 5 minutes including letting it idle to operating temp. Upper rad hose shot from 20 deg celcius to 50 when the engine temp hit 96, so seems to be working. Followed Ratchet's instructions regarding refilling and worked great! Going to check coolant level in a few hours.


Thanks for the pictures.
Did you install new gasket or RTV?
 

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If you remove the thermostat, how much coolant should I expect to drain from the engine/hose before the coolant level is below the opening? Or is it better to drain some from the radiator before starting?

Second question, are there any special tools I'll need beyond a good socket set?

Thanks for all the info so far.
 

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Discussion Starter · #37 ·
i drained a gallon and it was below
 

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i drained a gallon and it was below
I should have drained some, did not, my wide oil pan caught it all though.

All you need is a socket set and pliers for re/re the rad hose onto thermostat. Phillips screwdriver for bleeder screw too
 

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One more question. I know I'll need to pull off the air intake to get to the thermostat. On a 3.6 Laredo, do I need to pull off the plastic skid plate to get to the radiator drain valve or can I reach in there without removing it? Will I need to raise the car on jack stands?

I'm doing this on a friend's car and want to be sure we know what we're in for. Thanks again.
 

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Job all done. Thanks for the help. For those considering a few specifics on the VERY manageable repair.

You need to pull of the air intake system. See this video from 2:00-2:30. You'll need an 8mm socket to loosen the clamp on the housing (passenger side, near the jump point).

Draining 3/4 gallon of coolant got us below the thermostat level. 1/2 tubing fits on the radiator drain port, so we ran tubing past the plastic underpanel so that we could drain easily into a jug.

Bolts for the thermostat housing at 10mm.

The bleeder screw on the thermostat housing is a little difficult to reach once you re-install the air intake, but you can do it with the screwdriver angled towards the windshield.

No pics, but the ones earlier in the thread were super helpful.
 
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