Fault: Mapped thermostat cooling control

[yod88]

Looking to see if anyone knows whats going on here before i throw parts at the car...

Started the zhp yesterday and the service engine soon light came on, I plugged in my peake code reader and a code 279C "mapped thermostat cooling: control" came in...I ran some errands and reset the code then parked the car for the night. Started it this morning and almost immediately the service engine light came on again, same code was thrown, reset again and same result.

My thermostat is functioning "properly", car warms up normally, and maintains proper temps, no running issues with the car. I tried resetting the code again when the car was hot and after about 20 minutes it reared it head again.

My thermostat is about a year old with about 20k on it, so Im a little hesitant to just replace it, I wouldnt think it shouldve failed this early...

Has anyone else experienced this? If so, was it the thermostat itself causing the problem or something else?

Thanks,
Navid

[danewilson77]

What does your temp read as viewed via obc?

____________________________________



Incase no one knows here's how to do it.
Tests 1-2 are unlocked. Tests 1.2, 1.2 etc are known as sub-tests. Tests 3-21 are locked but Test 19 is the unlock function for accessing the displays.This should work with your vehicle.


TEST 01. - Vehicle specific data including:
SubTests:
12345 1.0 = VIN
7504 1.1 = Body number
690151 6_1.2 = Part number of cluster
039000 1.3 = Coding/Diagnosis/Bus Index
1102 1.4 = Manufacturing date (calender week/year)
06_110 1.5 = Hardware/software # of cluster (HW:06, SW:110)
1E5_06 3_1.6 = injection status, number of cylinders, engine factor

TEST 19. LOCK/UNLOCK
Sub-Tests
L-ON---
L-OFF 19.0 =
Displays changes from "L-ON" to "L-OFF" every second. To unlock test functions, press the cluster button immediately when it changes to "L-OFF". Tests are automatically locked when exiting test functions.

TEST 02. - Cluster System Test - activates the gauge drivers, indicators and LEDs to confirm function.

TEST 03. - SI Data
Sub-Tests:
1500 3.0 - Liters
0 3.1 - Periodic inspection days (not applicable for US)

TEST 04. - Momentary Consumption
Sub-Tests:
0267 4.0 = 26.7 liters/1000km
0073 4.1 = 7.3 liters per hour

TEST 05. - Distance Gone Consumptions
Sub-Tests:
0195 5.0 = 19.5 liters/100km
226 5.1 = momentary distance to go (226km)

TEST 06. - Fuel level sensor inputs in liters
Sub-Tests:
237415 6.0 = Fuel level aveg. *LH sensor input = 23.7 liters
*RH sensor input = 41.5 liters
0652 6.1 = Total tank level average = 65.2 liters
0667 1_6.2 = indicated value and tank phase *1 = both sensors OK
*2 = one sensor fault
*3 = implausible input

TEST 07. - Temp. and Speed
Sub-Tests:
032 7.0 = coolant temp. input 32C
245 7.1 = outside temp. input 24.5C
5283 7.2 = engine speed 5,283 RPM
058 7.3 = vehicle speed 58km/H

TEST 08. - Input values in HEX Form
Sub-Tests:
XXX 8.0-8.3 = Hex code, instrument cluster inputs

TEST 09. - Battery Voltage
Sub-Test:
125 9.0 = 12.5v

TEST 10. - Country Coding
Sub-Test
02 10.0 - US 02

TEST 11. - Cluster Code
Sub-Test
000003 11.0 = Cluster Code

TEST 12 - Not Used

TEST 13 - GONG Test
Sub-Test:
Gong 13.0 = Activate gon by pressing buttong (gong response is delayed)

TEST 14. - fault memory (NOT FOR DIAGNOSIS)

TEST 15 to 18

TEST 20. - Averg. fuel consumption - correction factor.
The factor follows previous systems, with adjustment range of 750 - 1250. The adjustment method is new for the base cluster. If adjustment is necessary, enter into test 20 using the cluster button.

The correction factor number is changed by using the sub-tests for the "ones, tens, and hundreds of the correction factor number. The digits will automatically scroll through 0-9 within each group (ones, tens, hundreds).

Sub-Tests:
XXX9 20.0 = Press the button when the correct "ones" position is attained.
XX5X 20.1 = Press the button when the correct "tens" position is attained.
12XX 20.2 = Press the button when the correct "hundreds" position is attained.

TEST 21. - Software reset
sub-test:
reset 21.0 = Reset Software.
Sent from Williamsburg, VA USA

[yod88]

Ill check on this in the AM...forgot you could do that with the OBC, thanks Dane

[danewilson77]

Ill check on this in the AM...forgot you could do that with the OBC, thanks Dane

Werd. Let us pnoooooo

Sent from Williamsburg, VA USA

[LivesNearCostco]

What kind of thermostat did you install a year ago, OEM? Maybe the plug that connects to the thermostat heater is dirty or loose?

[yod88]

So the OBC is reading 96C for coolant temp...so about 204F, doesn't seem too bad to me...

The tstat I believe is a wahler unit, but I can't remember for sure

[danewilson77]

completely normal.

http://www.zhpmafia.com/forums/showthread.php?6575-OBC-19.7.00-Watcha-go/page15&highlight=watcha

[yod88]

So is there anything else that can go wrong with the thermostat, even if the basic operation is fine?

[Meric]

It happens with Aliminium T-Stats usually.. The whole T-stat heats and tricks the built-in heat sensor which triggers CEL... Go with OEM or something not aliminium..

[yod88]

It happens with Aliminium T-Stats usually.. The whole T-stat heats and tricks the built-in heat sensor which triggers CEL... Go with OEM or something not aliminium..

are you referring to an aluminum body? because mine is made of the same materials as the oem one

[Meric]

So yours is plastic?

[yod88]

So yours is plastic?

yup, also found out that oem tstats are produced by wahler...so my unit is the same as the oem

I have another tstat that my buddy sent me off his car to test with, so tomorrow I should know whats going on

[yod88]

So today I swapped on the other tstat, that one has about 58k on it but was in working condition...no codes and the water temp is correct, so looks like this problem is solved

i guess the "old" tstat i have is defective or something failed that would trip the code but still have its basic function

[shanneba]

So is there anything else that can go wrong with the thermostat, even if the basic operation is fine?

Yes. There is an electrical heater element inside the thermostat. The ECU turns on voltage to the heater when the engine speed/load is over a set value.
That allows the thermostat to open more, cooling down the engine. That is what the electrical connector on the thermostat is used for.
The E46 thermostat is variable from about 180F-210F+ dependent on the engine speed/load (and a couple other factors)

Drill down here for more info: http://www.bmw-planet.com/diagrams/release/en/e46/index.htm

This characteristic map is determined by the following factors:
Engine load
Engine speed
Vehicle speed
Intake temperature
Coolant temperature
Design of the characteristic map thermostat
The characteristic map thermostat is an integral thermostat, i.e. the thermostat and thermostat cover make up one unit.
The principle mechanical design of the characteristic map thermostat corresponds to that of a conventional thermostat. However, a heating element is additionally integrated in the expansion element (wax element).