W212 E63 (5.5bi) oil temp sensor problem?

[vorstehund]

Hi

A week back I had a problem with the engine coolant fan suddenly starting to run at full speed whenever the ignition was on.

Many internet searches revealed this was a common fault, but the reason behind it could be anything that made the ECU think the engine was overheating, a fault in the ECU itself or a fault in a myriad of sensors, from AC to coolant temp etc.

I removed the ECU, checked connector seals etc, all OK.

I `solved` this temporarily by removing fuse F22. This had the knock on effect that a warning about oil level not being able to be measured comes up and the oil temp is not displayed. It also tends to sit too long in lower gears, presumably thinking the engine has not warmed, so not wanting to labour it.

I have just tried replacing the fuse and found that the coolant fan did not come on. Hurrah.

So I went for a drive and found that all was back as it should be, except that the oil temp was still showing zero, albeit no warnings were displayed.
The yellow engine light remains illuminated also.

It is all looking like the sensor is U/S, first presumably showing too high a reading hence the fan coming on and now completely open circuit and no reading.
The lack of warning messages is strange though.

Has anyone had a similar experience?

regards

 

[alexanderfoti]

Possible. The fan will come on when th ecu has a comms failure with a component. Get the codes read to identify the cause of the light and take it from there.

 

[vorstehund]

The peculiar thing is what happened after I replaced the fuse.

The oil temp is displaying zero, just the same as without the fuse, but now no warning messages, no fan on full and the gear changes are back to normal ranges.

Yet nothing has changed, the ECU still doesn't know what the oil temp is.

I bought a cheap OBD2 scanner but not had any success getting it to connect.

Any recommendations for one which definitely does work with Mercedes?

 

[PovertySpec]

I bought a cheap OBD2 scanner but not had any success getting it to connect.

Any recommendations for one which definitely does work with Mercedes?

iCarSoft series do but as you're in Dorset you could pop along to MBS in Southampton.

You could get it on STAR and have the results correctly interpreted on the spot for a third of the cost of a scanner.

 

[alexanderfoti]

iCarSoft series do but as you're in Dorset you could pop along to MBS in Southampton.

You could get it on STAR and have the results correctly interpreted on the spot for a third of the cost of a scanner.

+1 on this.

You may have a code that needs resetting before the functionality returns.

 

[vorstehund]

Southampton is about a 3 hr round trip and 120 miles total for me.

I have Star Tech about 20 miles away in Poole.

Bizarrely the oil temp is now working again and the only thing to show there was ever a problem is the engine warning light.

Ordered an allegedly better dongle that will work with Torque so see where that gets me.

Hopefully will be able to confirm the fault code as being the oil temp / level sensor and reset it.

Just love this complicated electronic logic stuff everyone insists on using.
After the first solar flare strike or air-burst thermo-nuclear device being dropped, nothing except old diesel Land Rovers are going to work

 

[PovertySpec]

Just love this complicated electronic logic stuff everyone insists on using. After the first solar flare strike or air-burst thermo-nuclear device being dropped, nothing except old diesel Land Rovers are going to work

Paging Craig!!

Sorry, didn't realise you were on that side of Dorset.

Advice still stands though re: STAR, it saves a lot of guesswork/throwing parts at it

 

[alexanderfoti]

You may find that the engine light goes off after a while then.

 

[television]

Yes lamp often goes away after 3 clear starts.

 

[anyweb]

you could get the quite cheap dashcmd for iphone (like i did) and with a Wifi ODBII reader read the codes and clear the errors using dashcmd

i find it quite helpful on mhy car and it works just fine on W212

 

[vorstehund]

you could get the quite cheap dashcmd for iphone (like i did) and with a Wifi ODBII reader read the codes and clear the errors using dashcmd

i find it quite helpful on mhy car and it works just fine on W212

I took the parallel Android route.

This bluetooth dongle works perfectly.
ELM327 OBD2 OBDII Car Bluetooth Scanner

For the price of about 3 mins at a dealer, couple it with the free Torque app and you are away.

Engine light cleared, no further errors reported, all back to normal.

Hurrah.