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The oil temp display started showing blank and the oil cooler fan came on full. I checked the codes, and it was giving me a 3719 (MB proprietary code) for "The Value of Component B1 (Oil Temperature Sensor) is Implausible". When I reset the code, the display shows a blinking -143 C but after a while that gets replaced with a blank (all underlines) display and the cooler fan comes on full. I read that -143C is a default that the ECU uses when it can't read the oil temp sensor. A curiosity is that when I looked at live data with my scanner it didn't show -143 C, it showed -40.9 F and every couple of seconds there was 1-3 blips of -32.8 F.
Engine Cooling Graph for 2011 MB E63 AMG (W212) M156
I suspect the oil temp sensor or it's connector but it's behind the A/C compressor and I see no way to get to it without removing, or at least loosening, the compressor which is no small feat in itself. I might be able to get to the connector on the ECU -- assuming it is any more accessible -- and test back through the sensor that way. It wouldn't determine whether sensor or connector, but the R&R is the same for either.
Does anyone know of a way other than these two options for determining whether the sensor/connection is good or not?
Thanks in advance,
Howard
Seattle
Last edited by Howard Woodard; Jul 25, 2025 at 03:38 PM.
I'll be happy to provide that info after it is fixed. Up to now it has always averaged around 212 F.
Man, I am not looking forward to getting to that sensor...
Howard
a lot of us know it's no picnic to get in elbow deep
> ELECTRICAL SEALS...
While working around your compressor use engine RTV sealant to waterproof the junction between harness wires coming into connectors.
Your sensor, compressor, ....
Seal everywhere you don't want water oxidation traveling up by capillarity.
Ive been having the constantly running oil cooler fan but Im not getting the blank temp readings; my oil temp readings seem to be ok and rise as the car warms up. Any ideas what would be causing this before I rip the car apart again and throw another new part that ‘might’ solve the problem???
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Testing the oil temp sensor...
