lee1981

Hi everyone, really need some help or advice, my 2009 Subaru sti 330s is playing up, as soon as I put the ignition on the temp gauge goes straight to hot and the cooling fans are on full whack straight the way! I have tried an new temp sensor and it is still the same, happens with sensor plugged in and disconnected!

please help!!!

cheers Lee

Blocks85

Give Enginetuner a call mate, I'll guarantee they will sort you out.
Cheers

lee1981

cheers mate, can anyone recommend a good one in Leicester area??

fez the plodder

Carnetix in Melton

joz8968

iTrader: (13)

Roger Clark Motorsport (RCM) in Brindley Road, Hinckley. About 12 miles away from centre of Leicester.

Matt Clark will sort it, I'm sure.

joz8968

iTrader: (13)

Or Graham Goode Racing (GGR) in Lutterworth Road, Leic.

JDM_Stig

iTrader: (3)

make sure there is water in it

joz8968

iTrader: (13)

Or the Subaru main dealer, Heritage Leicester, a bit further up Lutterworth Rd, opposite Grace Road.

riiidaa

iTrader: (2)

doesn't sound like an electrical fault

lee1981

cheers for replies guys, its the same if no water in it or not, I ve put the computer on it and it says it is 120 degrees!! and that is as soon as I put ignition on, temp stays at the top of the gauge and fans are on constantly!

lee1981

im hoping just to get some info on the coolant temp circuit and then I can look at if something has shorted out and making it think engine is hot and putting the fan on.

riiidaa

iTrader: (2)

RCM is near you, that's lucky

JGlanzaV

iTrader: (3)

How is rcm been near anyone lucky?! If you want a 1k bill to do a coolant temp sensor then I suppose it is lucky :L

Coolant temp sensor failing closed circuit will make the ecu see 120degs and bring all the fans on.

lee1981

Hi, that's exactly what I am trying to avoid a big repair bill! I have already changed the coolant temp switch (the one that sits under inlet manifold) but it is still the same) it was a genuine one from the dealer, I was thinking the same as you, but now I am think there must be a short circuit in wire somewhere....

JGlanzaV

iTrader: (3)

I havent looked at my subaru to be honest, but I know there are two on my Starlet, is it a similar set up? I know one the ECU reads, and one controls the fan.

Is it a two wire or single wire jobby?

If it is a two wire jobby disconnect it, find the pins in the ecu for it, unplug everything, then test it down to earth and see if you get a reading, obviously you shouldnt get a reading if it is okay.

lee1981

Hi its a 2 pin connector, one wire looks like it goes to the ECU and the other wire splits off and goes to some other sensors, I thought this was going to be a common ground but with the ignition on the wire gets 12v down it!

JGlanzaV

iTrader: (3)

What other sensors does it feed? It could be a common live for the sensors and they measure the return voltage going to the ecu to calculate the temperature etc?

lee1981

Hi, it looks like it goes to the map sensor, knock sensor and a secondary combination air valve whatever that is!

TimH

iTrader: (11)

Temperature sensor would not normally have a live feed. It is a thermistor (resistive) type, so one side is grounded and the other goes to the ECU where it would have a pull-up resistor to +5V.

Newage temperature sensors have a 3 pin connector, at least up to 2006, but I've not seen a hatch-onwards sensor so can't be sure.

lee1981

mine is a 2 pin connector, one wire (white) goes straight to the big connector on the bulkhead, I assume this goes to the ECU, the other wire a black one with a white trace seems to split off to map sensors, injectors etc, the black wire with the white trace has 12v with ignition on, the white wire has 3v with ignition on...

TimH

iTrader: (11)

The black with a white trace is sensor ground and should *not* be at +12V. Either you've accidentally measured it wrong, or your ECU is faulty, or there's a short somewhere.

Since that ground also goes to the MAF, throttle, knock sensor etc, I'm surprised the car is running at all.

TimH

iTrader: (11)

See attached.

lee1981

Hi, the wire that goes to the ECU has 4v, The other wire that splits of also goes the the map sensor and then the injectors, i was assuming this was a common earth, but i checked it again and it goes to battery voltage when the ignition is turned on.

The car takes a while to start up and it misfires and splutters low down, there is no fault codes other than p0117 which is low voltage to ECT sensor....

lee1981

Is that wiring diagram forr a 2009 sti? as the wire going to my ECT are a white wire and a black wire with a white trace??

TimH

iTrader: (11)

Wiring diagram is for a 2008 STi. I don't have 2009 diagrams but I would be very surprised if it was really any different - but I obviously can't be sure. But the colours don't match so maybe there is a difference.

Are you 100% sure it is the coolant temp sensor? For example, the secondary air pump has a two pin connector with a white and black wires? White would be +12V with ignition on, but the black should be ground.

Coolant sensor is, I believe, towards the front of the engine on the front of the crossover pipe.

lee1981

The sensor I replaced was underneath the inlet manifold on a metal pipe that ran one end to the other...?

lee1981

and when I un done it coolant came out so I am fairly sure it was the ETC sensor, is there only one sensor that controls the engine cooling system??

TimH

iTrader: (11)

Crossover pipe runs from one side of the engine to the other, at a slight angle. Definitely sounds like coolant sensor. Just realised that since the 2007-onwards use CANbus connections, that would be why its only a 2 pin not 3 pin sensor as the ECU feeds the instruments via CANbus rather than it needing a separate sensor feed.

Wire colours do vary from what the diagram says, so I wouldn't lose too much sleep over the colours, but I have never come across a coolant sensor that has a 12V feed to it.

TimH

iTrader: (11)

Look here for location of sensor on the crossover pipe.

lee1981

hi, yes the sensor on the pic was the one I changed, I have traced all the wiring and can not seem to find any faults anywhere!! I have had a lot of advice from some helpful people today, sccobyclinic seem to think that it is my headgasket that has gone and these are the symptom's of that? carnetix seem to think it is a wiring fault but obviously both of these companies need to see the car first.

So at the minute the car struggles to start, when it does it coughs and splutters, when driving there is now power, all the lights are illuminated on the dash (engine light, cruise, traction etc) the only fault code stored is p0117 engine coolant temp circuit and this code will not erase!

The temp gauge shoots up to hot as soon as the ignition is turned on, even if this is first thing when the engine has not even been ran up, the fans are on constantly and the gauge will not move from the hot position.
The scanner is showing that the engine temp is 120 even though it is stone cold!

I have done a compression test and it is around 150psi per cylinder.

Any advice would be much appreciated before I spend 3k getting the head gaskets done!

cheers Lee