Coolant light / Engine temperature problem

[CR55EDS]

Been having a problem with coolant light going on and off for some time now. Car is not a daily driver.

Coolant water level is perfect so not lack of coolant. Tried draining coolant and refilling. Same problem.Put new thermostat in car. Same problem. Basically I start the car and I notice the engine temp gauge in dashboard will get up to half way within 1 mile. However, it’s perfect as it always stays at halfway. Before, I think temp gauge used to take 3-4 miles before getting up to temp/ halfway. After 3 or 4 miles, coolant light will come on. Half a minute later will go off. Might come on again 5 miles later. It’s random.

Ran INPA and the attached shows up. Oil sensor needs replacing but that’s been gone for a while so I don’t think related.

Any thoughts. Could it be some sensors?

 

[patriot66]

Is the coolant temp sensor ok ? Fit a new one as they're not expensive

 

[CR55EDS]

I’ve read about there being 2 sensors. 1 at front , 1 behind the engine. Maybe I’m wrong? Anyone know which sensor I should be replacing and where is it?

 

[patriot66]

I believe the one in the radiator bottom hose connection to the thermostat is the radiator outlet temp sensor and is what trips the radiator fan. Photo was taken when fitting a new thermostat and waterpump to my car
The one in the rear of the engine block under the inlet manifold apparently reports to the instrument cluster temp gauge so maybe this is the one to check first. Photo was taken when I was replacing my CCV system

 

[Wc555]

Thanks patriot66 Photos speak a thousand words. That rear of engine block sensor looks a right buggers muddle to get to?? Should be fun

 

[CR55EDS]

Job done. Ordered Hella sensor off Amazon as BMW Parts Cardiff never rang me back and couldn’t ring them direct. I thought I’d have to take off Inlet manifold but was able to get a 22mm wrench around the back. Gave her a run and no coolant light so hopefully all sorted.

 

[firebobby]

My car has always got up to temp really quickly, at around a mile or two.

 

[patriot66]

Job done. Ordered Hella sensor off Amazon as BMW Parts Cardiff never rang me back and couldn’t ring them direct. I thought I’d have to take off Inlet manifold but was able to get a 22mm wrench around the back. Gave her a run and no coolant light so hopefully all sorted.

Fingers crossed

 

[colb]

That thermal oil level sensor code is in relation to the sensor in the bottom of the sump. Had that code on my 2.5 and changed the sensor when I changeed the oil. Take the undertray off to access it. Drain the oil then take the old sensor out (two nuts on studs) new sensor comes with o ring. Choice of makes and prices here https://www.onlinecarparts.co.uk/car-brands/spare-parts-bmw/z4-e85/16828/15030/sensor-engine-oil-level.html
Prices seem to have increased since I got mine I paid around £12 for the Ridex one for my 2.5. If you enter your car details on the site to check you get the correct one, example posted was based on 2003/5 3.0i 170kw engine.
Sounds like the new thermostat is working ok, hence the quicker warmup.

 

[Wc555]

Yeah. Bought a hella oil level sensor as well to do that job but having difficulty getting shield/protector with 8 x 16mm bolts off. 6 are off but 2 just won’t budge. Tried impact wrench as well. No good. Might get a longer ratchet to give me more leverage. Have sprayed wd40 but no good. I presume as bolts hanging down, wd40 no good anyway as cannot travel up?