Coolant temerature sensor

[Titan_br]

I have the 2AF9 ramdomly it come and goes. Let me ask you, when the sensor is off, what is the readings you get? Mine gets 400ºF or 207ºCelsius. Is this ok? Or should be negative?

[L4ces]

Originally Posted by Titan_br

I have the 2AF9 ramdomly it come and goes. Let me ask you, when the sensor is off, what is the readings you get? Mine gets 400ºF or 207ºCelsius. Is this ok? Or should be negative?

Why would the temp sensor be off? What parameter were you reading?
Does your engine fan run at high speed?


I have that code and replaced the thermostat, temp sensor, water pump and hoses. Problem persists. Check the health of the temp sensor connector.

[Assimilator1]

(Another thread revival ).
Did you get to the bottom of it?

I'm getting -

2af9 (coolant temperature sensor)
2b5a (intake air temperature sensor plausibility)

I haven't monitored the live readings yet, but I'm rather puzzled by the mention of the IAT sensor, do they share some of the same wiring?
Another odd thing, these codes aren't bringing the MIL on! Is that normal?? (Isn't for other cars I've worked on).

[edit] Well this is interesting, according to newTIS these 2 sensors (& others) share the same earth! Apparently it's here, looks like a pig to get to!

[///M3Fresh]

Originally Posted by Assimilator1

(Another thread revival ).
Did you get to the bottom of it?

I'm getting -

2af9 (coolant temperature sensor)
2b5a (intake air temperature sensor plausibility)

I haven't monitored the live readings yet, but I'm rather puzzled by the mention of the IAT sensor, do they share some of the same wiring?
Another odd thing, these codes aren't bringing the MIL on! Is that normal?? (Isn't for other cars I've worked on).

[edit] Well this is interesting, according to newTIS these 2 sensors (& others) share the same earth! Apparently it's here, looks like a pig to get to!

Its not too bad to get you once you get the intake manifold off. I would monitor the Coolant sensor first and see if that is getting a reading. Pull off the intake and sensor and swap it if you have 50k+ miles, they are cheap anyway and then see if the codes come back.

[Assimilator1]

Ok thanks.
I'm pretty sure with our snap on tool I can monitor multiple sensors at once, so I'll do that.
My car's got 75k on it, but I'm not replacing stuff unless it needs it .

Re the IAT wiring, I stumbled across this unusual repair in newTIS, unusual as a wiring repair like that wouldn't normally be mentioned unless theirs a specific problem, but it doesn't say .
Any ideas? (maybe faulty wiring or a plug causing spurious readings??).