Merc E350

Hi all. I don't know if someone can help. I have a 2013 E350 W212 and am occasionally have some strange issues where the temperature guage won't rise at all and the cooling fans come on. If I switch off the engine and switch back on again the temp guage goes up and the fans go off. It's not every time I drive it, just every now and again.

Thanks to everyone in advance for any help.

CaliBenzDriver

> RECAP:
Intermittent wrong temperature sensing once a while with supersonic fan on.

You have the conditions pretty well defined
so we can have a better focus!


> 1...2...3 Bingo:
All preliminary attention would be focused on sanity checking the temperature sensor (not the A/C pressure sensor).

However you've noted restarting the car clears this issue! We know the engine temp is doctored and posted on the CAN bus for the iCluster to display.

Essentially the ECU is distrusting the sensor for some reason then racing the fan as a form of cooling protection plus driver warning.

The $2,000 question then becomes: what failure causes the ECU to engage in safe-mode cooling ?



> PRELIMINARY CHECKS:
We want to rule out bad sensor circuit, unit or wiring.

1- Have a look at the connector to see if coolant is leaking through the pins into the connector.

2- Read the temperature data with your scanner when this happens.


> ADVANCED CHECKS:
We want to figure what pushes ECU over the edge.

1- Scan for ALL faults for health assessment.

2- Suspect something fancy or classic poor GND.


That means you may have a "no parts", labor only repair.
🤞
​​​​​​

Garrath

Did you figure out the problem? I'm having the exact same issue.