ODB2 error code P0125? Oxygen Sensor

[RattyMcClelland]

I posting on behalf of a friend. He bought a 2002 Galant v6 auto about 6months ago and ever since has been getting aweful MPG. Car runs great and no rich fuel smell apart from upon start up.
Also the battery light has always been on but no problems.

Today my mate went to kwik Fit (i know is ****e but we have a mate their so we get stuff for free and hes great mechanic). They plugged it in and wiped the codes and we drove it around to see if they returned.

They did.

Error code P0125 comes up - Coolant temp for closed loop fuel control fuel control insufficient.

Now coolant levels are fine. Heater etc all work fine.

I believe it could be an oxygen sensor or faulty sensor somewhere.

Any ideas?

[Kieran]

Error code P0125 comes up - Coolant temp for closed loop fuel control fuel control insufficient.

I'd listen to the diag code this time, it's not unknown for the coolant sensor to fail.

"But my temp gauge still works!" I hear you cry - There's two temp sensors. One feeds the gauge, and the other feeds the ECU. Sounds like the one to the ECU is on the fritz. They're both located on the pipework near the thermostat housing. Follow the top radiator hose back to the thermostat area, you'll see some alloy pipework there - they're on there. I can't remember which one's which now - I think the one nearest the radiator top hose outlet (the one with a single wire connection) is the gauge sender, and the one nearby is the one to the ECU.

That'll also explain the pants MPG - the ECU, thinking the engine is cold, will have been keeping the fuel mixture too rich.


BUT - get the battery light diagnosed too... It's not unknown for the diode/voltage regulator pack to blow in the alternator, and whilst it'll still charge the battery, you'll be getting a very "dirty" electrical signal - and this can make various sensors give odd readings. In fact, I'd suggest dealing with that first, clearing the codes, then proceding as above if the check engine lamp comes back on again.

And welcome to you (and your friend by proxy) to ClubVR-4!

[miller]

hey Ratty, welcome aboard CVR4! Arent you on Japmids too? I recognise the name! Honda Prelude?

[Atik]

Out of curiosity, what sort of MPG is he getting? for the V6, you should be expecting 30+ quite comfortably.

[RattyMcClelland]

hey Ratty, welcome aboard CVR4! Arent you on Japmids too? I recognise the name! Honda Prelude?

Yep thats me. im everywhere but Preludes mainly.
Will do all of the above cheers guys.
Hes getting around 200miles to £70 which is utter gash.

Cheers

[RattyMcClelland]

BUT - get the battery light diagnosed too... It's not unknown for the diode/voltage regulator pack to blow in the alternator, and whilst it'll still charge the battery, you'll be getting a very "dirty" electrical signal - and this can make various sensors give odd readings.

Would this cause the car to randomly cut out in town driving for now apparent reason and then after a while wont start up and cause all sorts of electrical issues like dim dials etc.
That happened but has not since.

[VR4WGN]

hi dude welcome if you become a full paying member you open a realm of archive information to help you along your way with your car..

[AlanDITD]

ratty from PUK?

[RattyMcClelland]

ratty from PUK?

The one and only!

[AlanDITD]

oh dear....stop worrying about your mates car and get yours fixed

[Davezj]

get a volt meter on you battery when the car is running and rev it. if the battery voltage goes high than 15V then the diode regulator is probably goosed and that will do the battery no good at all. engine off should be 12V engine idle should be about 13V-14V.

here is a link to what all the standard p codes mean for future reference
http://www.troublecodes.net/OBD2/Pcodes.shtml

[RattyMcClelland]

Well i just checked the voltage across the battery when engine is off and its 12.2v and when engine is on and idling its 14.4v When engine is reved to around 4k voltage remains at 14.4v.

So i take this as a good sign. Now to replace the Coolant temp sensor on the ECU side.
Dont suppose anyone has a part number so i go and buy one. Or a place where i can get a spare.
Id expect Mitsubishi to charge a fair wack for one.

Cheers guys.

[Davezj]

what is the chassis number of the car and i can get the part number for you. i take it is a euro spec galant and not a jap import.

i will look it up on ASA for you.

[RattyMcClelland]

Its the E8a8 with the 2.5V6 6A13 engine. UKDM.

[Kieran]

Its the E8a8 with the 2.5V6 6A13 engine. UKDM.

You mean EA5A.

[RattyMcClelland]

You mean EA5A.

Yes that makes more sence.