Engine fan on and erratic temp gauge P2279

[Goatz]

Hi all,
out of the blue my engine fan is running immediately from start up and to 5 mins after switch off.
i noticed The temp gauge wasn’t reaching 90 so replaced that.
just took it for a long spin and the problem persists. I noticed the temp gauge never reaches 90. It goes up to about 70 then drops back to 30. i had the car heating on at full blast and noticed that the temperature dropped off at the same time as the gauge did.
I popped the coolant lid to clear any air locks but this didn’t make any difference.
i have and eml P2279 intake air system leak. This is not a ghost code as I cleared before I drove.
car drives fine. I do did not find any split hoses.
I am thinking the thermostat housing might be the cause?
any help appreciated.

G

 

[RCZIain]

The fans running will probably be because of the DTC. The fans ran flat out on my RCZ when a coil pack failed.

 

[Jumper]

What engine is it and have you had/done any work/engine mods recently? If its a 156 I'd say you need either a new Temp Sensor on the coolant bottle or a new Thermostat Housing if youve not had any work done. If you have had the engine modded i.e air filter and inlet modifications then make sure all the hoses are on tight with no leaks plus check the PCV hoses front and back as un metered air can cause the fans to go crazy.

 

[Goatz]

Hi, no recent work.
I replaced the engine temp sensor yesterday and the problem persists.
if It was an air leak would the temp gauge jump around like this?

it is a 156 petrol

 

[RCZIain]

I never really noticed with mine, but I'd assume your temp gauge is yoyoing because the cooling fan is running fast.
Is the code from Planet or a generic reader?

 

[Goatz]

it’s a generic reader.
the yoyo’ing is happening fast, takes a while to get up to 70-80 then drops to 30 in around 5 seconds and then repeats. I would be amazed if the fan can cool it down that quickly, but I’m no expert.

 

[Jumper]

Thats pretty erratic moving every five seconds. My best guess is new Thermastat Housing but check all the air hoses and PCV hoses just incase they have worked loose.
Because P2279 is associated to un metered air in the intake manifold I had the same error code when my PCV hose came loose at the back of the engine and it was sucking in fress air into the intake manifold. Once I found it and secured the hose it didnt go away (crazy fans/temp gauge going nuts) untill I drove up the motorway and back 60 miles and reset itself.

 

[Pedro]

Usually its the sensor that is the culprit can't see that tank causing any issues there again another forum member Trevor had the same problem & his new sensor was faulty?

 

[Goatz]

going to take it to a garage tomorrow. I can’t get under the car to check for split hoses. I am hoping they will spot one around the manifold.
if not I might ask them to change out the thermostat.

 

[Goatz]

so I went to the garage, I left the car on and while I was filling out the forms the fan switched off. Everything seemed fine so I drove home. Temp gauge was sat at 90 the whole way. Perhaps the new sensor needed some time, or t was just a intermittent fault.

 

[Goatz]

Quick question, I am wondering if I forgot to replace a check valve after I replaced the air intake turbo hose and breather pipe.
is there a check valve here on the 156? If so, where does it go?
thanks

 

[Pedro]

Not sure if they have one with the air intake also you may get a lean burn going on without any signs if its a vacuum leak
Have you had a smoke test done as the P2279 can primarily be triggered on the metered side of the Maf sensor
Stupid question but is your battery fully charged some codes can actually be thrown up from low voltage faults?

 

[Goatz]

No smoke test.
batt was fine before the fan flattened it. It’s coming back now though.
I don’t recall seeing a check valve when I removed the old hose.
where is the MAF sensor?

 

[Pedro]

The Maf is in front of the Airbox/Filter intake you will see the plug on the top

 

[Pedro]

There is some truth to this in all modern petrol Engines same goes for the MAP sensor