P0128 randomly came up

[x_orange90_x]

2017 Dodge Journey GT AWD 3.6L 110k Miles

 

A couple days ago I was on my way home from my in law's house and while driving the Engine light came on. I was right about in the middle of my 25 minute drive, engine warmed up and running fine. I pulled the code when I got home. It was pending and so I left it to see if it would go back off but it has not. The temperature gauge is going to the normal range, the heat appears to work fine, and nothing else seems obviously wrong. I've been reading that there are several things that CAN cause this code, not most of the time it's the thermostat. I don't want to take guesses at it and start replacing random parts, so I figured the experts here could give me an idea based on their experiences. It was in the 40s I think at the time it came on, and being October here in Michigan it's getting colder now. I can't stand NOT having remote start 🥶

[larryl]

 

Sometimes the thermostat opens and the car doesn't warm up to proper temp.

Mine has done it a few times but I just clear the code I don't mind it running a little cool and the remote start will work

Edited October 15, 2024 by larryl

[x_orange90_x]

1 hour ago, larryl said:

 

Sometimes the thermostat opens and the car doesn't warm up to proper temp.

Mine has done it a few times but I just clear the code I don't mind it running a little cool and the remote start will work

I was thinking it might be a fluke. The coolant is at the bottom of the COLD range, so it is a little low but probably not enough to trip the sensor. Also, the fan DOES switch on and off with MAX A/C on, so that's working properly. I watched it warm up leaving work today and within 3 minutes it was at 110 and after about 15 minutes of driving it was around 210-215.

 

I think I may just clear the code and see if it comes back.

[Dean H]

 

P0128 Thermostat rationality.

 

Theory of Operation- 

 

The Thermostat is considered malfunctioning if the coolant temperature does not reach the highest temperature required to enable other diagnostics, or the coolant temperature does not reach a warmed up temperature within 20°F of the Thermostat regulating temperature. The Powertrain Control Module (PCM) creates a model of the engine coolant temperature warm up cycle, based on the engine coolant temperature at start up, ambient temperature, vehicle speed and engine speed. The modeled engine coolant temperature is compared to the Engine Coolant Temperature Sensor reading. If the engine actual temperature reaches the calibrated temperature threshold before the model, the diagnostic passes and completes.

 

If the model reaches the calibrated temperature threshold before the engine actual temperature, a pass/fail determination is made based on the difference between the model and actual values. The diagnostic is considered passing if the difference between the engine actual temperature and model is acceptable when the model is greater than the engine but represents the slowest possible warm-up for a "good" thermostat.

 

When Monitored and Set Conditions

 

When Monitored: This diagnostic runs when the following conditions are met

 

With the engine running.

 

Start up coolant temperature less than 65 deg * C (149 deg * F)

 

Ambient temperature between - B deg * C (17.6 deg * F) and 50 deg * C (122 deg * F)

 

Average vehicle speed greater than (10 coolant temperature reaches 85 deg * C

 

Engine speed does not go above 5400 rpm for more than 32 seconds

 

The pass/fail determination point is reached when the coolant temp model reaches 88 deg * C 190 4°F)

 

Set Conditions:

 

The predicted coolant temperature reaches the target threshold before the actual coolant temperature and the PCM detects that the actual engine coolant temperature is too far below the what is acceptable for a good thermostat

 

Default Actions:

 

MIL. light will illuminate

 

Possible Causes

 

--- LOW COOLANT LEVEL

 

--- COOLING SYSTEM ISSUES

 

--- THERMOSTAT OPERATION

[Dean H]

Remote Start Operating Conditions.

 

In order to operate remote start, the following conditions must be met-

 

Key fob sequence must be operated within a 100 meter range of the vehicle.

 

The vehicle must be in Park

 

Fobik is not in the vehicle

 

The hazard switch off

 

Vehicle Theft Alarm or Panic is not alarming

 

Doors and hood must be closed.

 

The battery voltage is normal (11 to 15 volts).

 

--Remote Start Shut Down/Deactivate Conditions---

 

Engine will NOT start or will shut down/deactivate during any of the following conditions below.

 

Doors or hood are opened before remote unlock

 

Hazard Switch depressed

 

Panic or theft alam active

 

Brake applied. If the vehicle is remote started and the customer then unlocks and enters the vehicle, the brake application will not stall the vehicle If the vehicle is remote started and no entry is detected, brake application will shut down the engine

 

Low fuel levels, Fuel indicator active

 

A prior remote start cranked the engine, but failed to start the engine.

 

Battery voltage NOT in the normal range.

 

High (run away) or Low Idle (stall) RPM.

 

MIL Active.

 

High Engine Coolant Temperature.

 

Low Engine Oil Pressure.

Edited October 18, 2024 by Dean H

[x_orange90_x]

Okay I'm back! So since creating this thread I have had the code come back several times, probably once or twice a week. I just reset it and go for another few days. Well yesterday morning I was smelling coolant and so I checked it when I got home. Sure enough I'm losing some. The reservoir is not empty yet, but it's down near the bottom. I noticed a small puddle as I was leaving this morning. It looked to be centered under the front of the engine. I definitely need to investigate it further but we're currently under a Cold Weather Advisory with wind chills in the -20s, so I am not getting under there for a few days! 

 

What are the common areas that slow leaks spring up? Btw, I'm at 117k miles now. I read on another thread about the oil filler cap assembly and how disturbing it too much can cause a coolant leak...? Well I did just have the oil changed in November.

[2late4u]

water pump weep hole is one slow place,and the  coolant jug and hoses for another, have you replaced the thermostat since having your problem? it is so easy to do and fairly cheap as well just replace with the right coolant,not so cheap but important,,,on your leak you need to see which side of the eng it is dripping from, if the oil cooler is leaking it will probably be dripping from the drivers side towards back side of the eng,,, also if the water pump it would be the passenger side of the eng,,,also SO easy to see if the oil cooler is leaking water or oil just remove the cover off the top of the engine and use a strong led light and look straight down alongside of your oil filter housing it should be clean and dry at the bottom of you see anything you might have a leak there

[John/Horace]

Start driving with a jug of coolant in vehicle so you don’t get stuck in the cold. Keep the reservoir at half if possible until you get leak fixed. 
 

You might have more than one problem going on at once. The leak is the main priority, clearing code permanently is second. If water pump weap hole is dripping (bad main shaft bearing seal) it will drip right at the front of the engine, so drivers side coming down. Milage is a little low for that, but it’s possible. 

 

If you have rear heat there is a plastic tee fitting in the large 1.5” hose that will feed rear heater core. Leak would be high up at front of engine, right around the middle. If fitting snaps you won’t be able to drive anyway, system will empty in mins at most.

 

Most likely leak is the oil cooler heat exchanger assembly. Mine failed at 100k miles, bottom oil seals let go. It’s mounted between the vee  of the cylinder heads, on the top of engine. Usually they gush oil but glycol is also possible as it heats/cools the engine oil flowing through it. Plastic get brittle and/or o ring seals let go under pressure. Most people switch to an all aluminum style unit, they don’t seem to fail a second time. The units with black are the plastic units. Engine oil filter is part of the assembly. It’s located under the plastic intake manifold, so hard to see. The two screw in sensors are oil temperature and pressure. 
 

 

 

 

 

 

 

 

 

https://www.rockauto.com/en/catalog/dodge,2017,journey,3.6l+v6,3434428,engine,oil+filter+housing,12429

Edited January 22 by John/Horace

[x_orange90_x]

10 hours ago, John/Horace said:

If you have rear heat there is a plastic tee fitting in the large 1.5” hose that will feed rear heater core. Leak would be high up at front of engine, right around the middle. If fitting snaps you won’t be able to drive anyway, system will empty in mins at most.

 

Hmm. I DO have the rear heat.. But I noticed about a week or two ago that it's not actually working 🤔 no matter what I set it to (manual, auto, High heat, etc) it still puts it cold air

[John/Horace]

Fix glycol leak on engine first.  Water pump leak would be passenger side of engine, I mistakenly said drivers side. Aluminum engines like the 3.6 don’t respond to over heating, get wrecked fast. If low glycol rear heat won’t work. Don’t add quick fix sealer additives, they can plug up heater core etc, find source of leak.

 

Like 2late4u said. Remove top beauty cover and shine light down around oil filter housing on top of engine. Should not see any red glycol sitting between the cylinder heads. Most of time the oil cooler gush oil on failure; but glycol is possible because two of the bottom ports in pic feed right into cooling jacket of engine.

 

In theory you could just replace the bottom set of o ring seals (new unit comes with new seals installed) on current cooler.  But better move is to replace with a whole new aluminum made unit. They were not available when mine failed in 2018 so I used an oem plastic unit. These coolers are used on Jeeps, rams and lots of other 3.2 and 3.6 engines. It’s one of the few flaws on a decently reliable engine. Aluminum oil cooler assembly is around $200 taxes in shipped.

Edited January 23 by John/Horace

[x_orange90_x]

11 hours ago, John/Horace said:

Fix glycol leak on engine first.  Water pump leak would be passenger side of engine, I mistakenly said drivers side. Aluminum engines like the 3.6 don’t respond to over heating, get wrecked fast. If low glycol rear heat won’t work. Don’t add quick fix sealer additives, they can plug up heater core etc, find source of leak.

 

Like 2late4u said. Remove top beauty cover and shine light down around oil filter housing on top of engine. Should not see any red glycol sitting between the cylinder heads. Most of time the oil cooler gush oil on failure; but glycol is possible because two of the bottom ports in pic feed right into cooling jacket of engine.

 

In theory you could just replace the bottom set of o ring seals (new unit comes with new seals installed) on current cooler.  But better move is to replace with a whole new aluminum made unit. They were not available when mine failed in 2018 so I used an oem plastic unit. These coolers are used on Jeeps, rams and lots of other 3.2 and 3.6 engines. It’s one of the few flaws on a decently reliable engine. Aluminum oil cooler assembly is around $200 taxes in shipped.

I will start looking for the leak today.. The temps have warmed back up into the 20s so I won't get frostbite 😏

 

I have an extended coverage plan through WYNN that has a few thousand miles left on it before it expires. Any idea if this would be a covered repair? I haven't even attempted to use the warranty because I've heard so many bad things about them 😒

[John/Horace]

Deductible is a big issue with warranty claims. It is approx 2 hours in labor and then the approx $200 part. Good idea to change plugs while in there, if they haven't been done, I think 100k mile recommended change interval.

 

Sometimes a bad warranty is better than no warranty. Could get independent no insurance quote first; keep that under your hat and see what warranty guys come up with. Weasel clauses with warranty coverage can be an issue.  At least parts supply issues from covid mainly over now.

[x_orange90_x]

On 1/23/2025 at 12:18 PM, John/Horace said:

Deductible is a big issue with warranty claims. It is approx 2 hours in labor and then the approx $200 part. Good idea to change plugs while in there, if they haven't been done, I think 100k mile recommended change interval.

 

Sometimes a bad warranty is better than no warranty. Could get independent no insurance quote first; keep that under your hat and see what warranty guys come up with. Weasel clauses with warranty coverage can be an issue.  At least parts supply issues from covid mainly over now.

I finally was able to take a look. Didn't see anywhere obvious that it's coming from, but the top of the transmission is SOAKED in antifreeze. Does that give an indication of where it's coming from? Also, there is a puddle of oil under the filter housing, however it's been there for months. I know this because my buddy pointed it out when we were replacing a bad fuel injector. As for the spark plugs, I replaced them at 96k and also replaced the trans filter and fluid.

Edited January 24 by x_orange90_x

[x_orange90_x]

Here's a couple more photos.

[5rebel9]

From your posted pictures.....   3 things I would check.

 

{1} coolant hose and connection to the oil filter housing assembly

{2} possible cracked coolant assembly OR a poor quality unit had been installed and is leaking on the 2 bottom ports under the assembly as in the pictures of the unit posted on this thread.

{3} Check the condition of the transmission oil with your engine dipstick for "milkyness" of coolant mixing with the transmission oil. . From your picture, the transmission vent valve looks rather "funky".

 

IF it is the engine filter assembly, GET THE ALUMINIUM replacement!!!

 

[x_orange90_x]

43 minutes ago, 5rebel9 said:

From your posted pictures.....   3 things I would check.

 

{1} coolant hose and connection to the oil filter housing assembly

{2} possible cracked coolant assembly OR a poor quality unit had been installed and is leaking on the 2 bottom ports under the assembly as in the pictures of the unit posted on this thread.

{3} Check the condition of the transmission oil with your engine dipstick for "milkyness" of coolant mixing with the transmission oil. . From your picture, the transmission vent valve looks rather "funky".

 

IF it is the engine filter assembly, GET THE ALUMINIUM replacement!!!

 

This is the driver's side, but you probably know that already.

 

I watched a YouTube video of another guy with a Pentastar, I think it was a Grand Caravan or Town and Country.. But his leak was on the driver's side from sort of quick disconnect L-shaped fitting. It came as part of the coolant assembly that had a Y connector and other hoses. You could see it literally dripping in his video. I will wait until I get the engine warmed up and see if I can find it dripping anywhere. It's been ending up on the ground everywhere I go lately, that's for sure. 

 

Also, the coolant in the reservoir looks reddish in color. Is that the new "purple" coolant, or a discolored older orange? Finding very conflicting info on Google about the proper coolant.

[x_orange90_x]

Can I use THIS to top off??

https://www.walmart.com/ip/1223953210?sid=f890ad6a-9dfa-4908-b6be-f17fbdcd3a17

 

Edited January 24 by x_orange90_x

[John/Horace]

You have the right guy responding to you, 5rebel9 has more 3.6 experience than anyone else on the site.

 

Top of engine will collect a bit of oil even from oil filter changes. If oil cooler has a real-oil leak, you can wreck engine quite fast. Will pour quickly out on driver side of engine compartment because that end is open more. Glycol would also be similar. 
 

I had glycol drip at front of engine below pump pulley, just before 100k miles. That is usually pump bearing seal failure, turning pulley without belt it was quiet and no excess play. But I bought new pump and aluminum style gasket anyway. Turned out small section of shim gasket had corroded away and created the drip, pump was fine (not common fail on 3.6 engines, esp at 100k). Changed it anyway after spending 2+hrs taking apart. No glycol issue since, changed thermostat (a wear item) since system was emptied out. Oil cooler failed 20k later, only oil leak occurred.

 

Up to around 2012 HOAT was the orange fluid, it’s now all OAT organic acid tec and purplish orange color. Not compatible don’t mix them. Can gel  up heater cores if wrong fluid used.

 

Clean up as much fluid as you can and run engine with beauty cover off, clean cardboard under engine. Look for main source. Van has diff cooling lines than Journey. But plastic tee that feeds rear heater core is known to fail early, oil cooler lower orings could also start weeping a bit. First pic is a new water pump gasket alum shim.

 

 

[John/Horace]

You should have  OAT in system from factory and it’s actually orange color .

This is what I use, the original since 2013 OAT coolant, not HOAT !

I prefer to stay away from universal stuff. Safest is dump and flush and refill with same kind after leak fixed.

 

Edited January 24 by John/Horace

[x_orange90_x]

4 minutes ago, John/Horace said:

You should have  OAT in system from factory and it’s actually orange color.

This is what I use, the original since 2013 OAT coolant.

I prefer to stay away from universal stuff. Safest is dump and flush and refill with same kind after leak fixed.

 

See, this is the coolant confusion I keep encountering. You say since 2013 it's OAT ORANGE. Everything I read online says OAT is purple. Mine looks reddish, but I seen a post another forum comparing the purple in different containers and it will appear red and even orange surrending on what it's in 😒

 

I need to get coolant right after work and top it off because it's well below the COLD line on the reservoir. I need to put something in there now. I think I'm going to go with this purple universal mix.

 

Coolant on a paper towel:

[5rebel9]

I was understanding that you RECENTLY bought this vehicle. That is why I suggested that the oil filter/cooler assembly MAY have been replaced BEFORE you got it and MAY be a poor quality unit.

There have been "issues" with the engine oil side cracking and causing leaks AND poor quality replacements not sealing properly on the O rings of the bottom side.

 

Yes, I have 3 3.6 motored DJ's and my '13's had to be replaced TWICE. the second time was due to the plastic base cracking under the cooler  due to a poor quality unit and failed after just THREE MONTHS. it got replaced with the aluminum unit. Only my oldest and most miles '11 has the ORIGINAL oil filter/cooler PLASTIC assembly. YES it's a fairly involved job to change out and known Plastic unit problems make the aluminum unit the best choice.

 

Unfortunately even with pictures being posted, it is almost impossible for a forum to "pinpoint" the source of a leak

 

MY understanding is that "newer" years coolant color OE is a PINK/ REDDISH color from approx. 2015 and up.  Color between different manufacturers of coolant don't seem to standardize well anymore, LOOK for OAT or HOAT designation.

 

 Mine are all high mileage and have been apart{coolant drained completely} so I use the Yellow universal coolant with NO PROBLEMS from it.

 

Good Luck!

[John/Horace]

Older HOAT was clearly orange newer OAT is called orange but yeah sometimes closer to red or purple.

 

Its the word OAT that matters , or OAT compatible, not the color.  I prefer using real  OAT to avoid compatible/universal risk (at least in my mind). Owners manual in 2014 says OAT so will your 2017. The purple is not saying OAT on it that I see. Spec is  Chrysler MS7170 or MS9769 or SAE J1034.

You will be dumping it soon to fix leak anyway, universal short term shouldn’t be issue.

 

[x_orange90_x]

The prestone I linked to says Compatible with: OAT, POAT, HOAT & G05

 

So I checked twice with the engine warmed up and running and cannot see a single drip. The fact that the entire transmission is covered makes me think it's spraying big time, but I only added a little less than a half gallon back into the system to get it back to full. Also, despite filling the coolant back up and driving, the rear heat vents are still blowing cool air on Max Heat no matter what I set it to.

[2late4u]

only a half of gallon?   I would take it to the spray car wash and spray the hell out of the area with soap cleaner then rinse it off and then take it for a good long drive to get it dry and then keep a close eye on any new wet spots,that will be your only way to find the leak, have to get it under a hot pressure condition to find your leak,,,good luck

Edited January 25 by 2late4u

[John/Horace]

Quote

 

Sounds frustrating. It might just be a steady drip on one of the connections, must be close to 20 clamps. Below is pic of rear heat supply return lines. Leak would likely be lower down on subframe if that’s cause. If you spray off glycol, be gentle don’t spray close up. Easy to damage stuff under hood.