Odd M62TU 88C thermostat BMW code 0x8B / 139 or PeePee code P0128

[geargrinder]

Just another data point to this situation... Starting new thread to put the proper error codes in the title instead of just the weakass Peeee code.

https://www.bimmerforums.com/forum/s...rmostat-(540i)

Car was fitted w the 88C in the fall, and a carefully wired resistor in the plug.
After months of winter and spring driving on the new stat without issue, I suddenly got an SES light.
Same code as ref'd above (0x8B/0139). Only notable issue had been heatwave 90's temps on prior days.

Cleared and drove for a other day or so. All was fine, then popped the SES again, same code. This time, temps had been opposite - cold mid 40's.

Reset again, and 2 weeks of mixed driving , no return yet, but waiting for one. When I have a chance, will post the Dme Software numbers.

That's all I got for now.

[peter540]

Welcome to the club!

[philly98540]

In

[geargrinder]

Scanned car this morning, the 139 is there but has yet to trigger an SES. That means it is one of those 'trigger light only after X occurrences' type of codes.

Used INPA so I get so much more info than PASoft/OBDgeneric stuff:
German descrip is "Thermostat klemmt" meaning 'thermostat stuck' i believe.
Occurred once so far
Last occurrence -
1800RPM,
motor temp 93C,
outside temp 22.5C
"Actual implausible" and "Initial implausible"

[gmak]

Have you checked that the resistor is still good?

[geargrinder]

ECU software info for my car... Can find w/ the Ident/Info buttons in INPA.

Program ("BMW Part number" or "hardware number"): 7532675
Data ("software number"): 7533585 (although for my car this is a bit misleading as its the VF tune so its based on that number but with whatever tweaks).

If we could pull that info from other 2002 cars that have this issue and some cars that DON'T have this issue, we might narrow down which ones have the fussier t-stat logic.

- - - Updated - - -

Have you checked that the resistor is still good?

Well... I doubt that's the issue, since the error seems to be about the temp being implausible, not the t-stat 'looking bad', but I can check it. I am pretty sure this is about validating temp ranges under certain conditions, and 't-stat stuck' is the DME saying "WTF bish, this engine is running TOO COLD man!" but... sure worth a double check.

Maybe later today after I get my alignment disaster sorted out, and when scottieducati comes over to fix his sunroof...

[peter540]

Daggum it,GG, you jinxed me. Got that pesky SES Pee-Pee 0128 again this morning. KTMP was 93°. Same exact thing two days ago.

I don't have INPA or PAsoft, so I can't see my DME version. Looks like I need to finally bite the bullet and buy the cable and software. Can they run on Windows 10? I only have one laptop, and that's its Windows version.

All that said, I'm more tempted than ever to just have DUDMD delete this code permanently -- I don't want to have problems again getting the car through its emissions inspection. Of course, the downside of that is if the thermo really DOES go bad, the car won't be able to alert me about that.

--P

[philly98540]

Dud is likely fastest and easiest way to eliminate this. Some intense sleuthing in the code, with the Damos overlay, and it likely could be found and turned off.

[geargrinder]

if the thermo really DOES go bad, the car won't be able to alert me about that.

--P

Oh the car will alert you alright. You just mught not like how it does it.

[Mach540]

Peter540, what does your KTMP read in key position #1?

I'm thinking that the DME uses that temp for engine management, and the key position #2 KTMP is just what you see on the OBC.

GG, same question.

[geargrinder]

Update... Apparently Terraphantm can fix this problem for people w/ his flash tweaks (along with being able to fix diff-ratio cruise problems and a few other things...) Note he tweaks the PWM curve as well to increase fan speed to account for the extra cooling required... GOOD stuff all up in here...

https://www.bimmerforums.com/forum/s...4#post29774254

[geargrinder]

Continued here - particularly a warning that this code can be dangerous:

https://www.bimmerforums.com/forum/s...ee-code-P0128)