Radiator Fan Running Constantly but Temp Gauge is at Middle point - codes inside

[mrpeterparker]

Hey all,

I'm a little perplexed by this as I would've thought it was a failed thermostat, however the temp gauge isn't really showing typically symptoms of a stuck thermostat. How often does the Coolant Temp Sensor actually fail?

Here is the code dump.

Thanks in advance for any insight!

6 Faults Found:

8113 - Performance Malfunction in Cooling System 
          P2181 00 [101] - -
          Not Confirmed - Tested Since Memory Clear
             Freeze Frame:
                    Fault Status: 00000001
                    Fault Priority: 2
                    Fault Frequency: 1
                    Mileage: 130754 km
                    Date: 2023.03.13
                    Time: 15:29:09

                    Engine RPM: 2213.50 /min
                    Normed load value: 28.6 %
                    Vehicle speed: 111 km/h
                    Coolant temperature: 61 ∞C
                    Intake air temperature: 6 ∞C
                    Ambient air pressure: 990 mbar
                    Voltage terminal 30: 14.800 V
                    Unlearning counter according OBD: 40

33160 - Engine Coolant Temperature Sensor 3 
          P01E4 00 [096] - Implausible Signal
          Intermittent - Not Confirmed - Tested Since Memory Clear

30226 - Engine Temperature too Low 
          P3081 00 [096] - -
          Intermittent - Not Confirmed - Tested Since Memory Clear

11786 - Sensor for Cylinder Head Temperature 
          P017B 00 [096] - Implausible Signal
          Intermittent - Not Confirmed - Tested Since Memory Clear
             Freeze Frame:
                    Fault Status: 00000001
                    Fault Priority: 2
                    Fault Frequency: 1
                    Mileage: 130756 km
                    Date: 2023.03.13
                    Time: 15:30:49

                    Engine RPM: 2117.50 /min
                    Normed load value: 45.5 %
                    Vehicle speed: 89 km/h
                    Coolant temperature: 58 ∞C
                    Intake air temperature: 2 ∞C
                    Ambient air pressure: 990 mbar
                    Voltage terminal 30: 14.720 V
                    Unlearning counter according OBD: 39
                    Engine status: COENG_RUNNING
                    Engine status-Test_Program_Co Eng st COMPU VERB UBYTE: 3

15851 - Performance Malfunction in Cooling System 
          P2181 00 [101] - -
          Not Confirmed - Tested Since Memory Clear
             Freeze Frame:
                    Fault Status: 00000001
                    Fault Priority: 2
                    Fault Frequency: 1
                    Mileage: 130754 km
                    Date: 2023.03.13
                    Time: 15:29:09

                    Engine RPM: 2223.50 /min
                    Normed load value: 27.8 %
                    Vehicle speed: 111 km/h
                    Coolant temperature: 61 ∞C
                    Intake air temperature: 6 ∞C
                    Ambient air pressure: 990 mbar
                    Voltage terminal 30: 14.800 V
                    Unlearning counter according OBD: 40
                    Engine status: COENG_RUNNING
                    Engine status-Test_Program_Co Eng st COMPU VERB UBYTE: 3

11510 - EVAP System Temp Sensor 
          P2025 00 [237] - Implausible Signal
          MIL ON - Confirmed - Tested Since Memory Clear
             Freeze Frame:
                    Fault Status: 00000001
                    Fault Priority: 2
                    Fault Frequency: 1
                    Mileage: 130777 km
                    Date: 2023.03.13
                    Time: 18:52:48

                    Engine RPM: 0.00 /min
                    Normed load value: 0.0 %
                    Vehicle speed: 255 km/h
                    Coolant temperature: 64 ∞C
                    Intake air temperature: 6 ∞C
                    Ambient air pressure: 990 mbar
                    Voltage terminal 30: 12.120 V
                    Unlearning counter according OBD: 40
                    Engine status: COENG_FINISH
                    Engine status-Test_Program_Co Eng st COMPU VERB UBYTE: 5


Readiness: 0000 0000

[Smac770]

You need to monitor the actual coolant temp sensors and see what they are actually doing.

G62 is the coolant temp sensor on the cylinder head. You can unplug the harness and test the resistance across the sensor pins, should be "2,250 Ω (+/- 750 @ approx. 20° C)".

G83 is the coolant temp sensor at radiator outlet. You can test it the same as the G62.

The P2025 likely means the temp is more than 25°C different from the coolant temp or the intake temp. So that's probably just a byproduct.

vehicle speed
outside air temp
coolant temp (G62 measured)
coolant temp at radiator outlet (G83 measured)
coolant temp at engine output specified (G62 expected)
coolant temp at radiator outlet specified (G83 expected)
coolant temp diff between engine and radiator
temp sensor for engine temp management: target
temp sensor for engine temp management
engine oil temp
oil temp sensor 2
calculated oil temp

That's 12 values (all VCDS lets you log at one time). So I'd log that and then process the data in Excel to see where the illogical occurs. If a sensor seems disconnected from the rest, maybe an issue with it. If the temp just never seems to come up to target, maybe a thermostat issue. The B9.0 electrically managed thermostat is definitely not a poster child for reliability.

[mrpeterparker]

Awesome. Appreciate all the detailed info.

To make matters worse - the symptoms and CEL all disappeared today.

I’ll log the all of the above when it returns.

[Smac770]

Yeah, bad case would be a wiring issue or a flaky sensor so it's errant manner is random.

[S4'ed]

Almost looks like all the temp sensors lost the common +5V reference voltage.......open circuit or short circuit wiring issue?
All 5 temp sensors failing at the same time is not likely.

SMAC770: What the hell is an "EVAP" Temperature sensor???

[Smac770]

The J909 fuel tank leak detection control module has a temp sensor in it, to be used in conjunction with the G400 fuel tank pressure sensor, for assessing fuel tank state. The J909 replaces the old V144 leak detection pump system. Just like the TPMS sensors read both temp and pressure inside the tire, the J909 needs both the temp and pressure inside the tank to really compute accurately.

Some background info on the config:
https://static.nhtsa.gov/odi/tsbs/20...21304-9999.pdf

Some more information on the J909 system:
https://forums.ross-tech.com/index.p...92/post-151429

So this sensor is built into the J909 and is in the fuel tank area, it gets 12v from a fuse in the left rear fuse block. Independent of anything in the engine bay.

[S4'ed]

Interesting, they added a temp sensor to get rid of the motorized vacuum pump.
Thanks for the info!