Check Engine Light '01 BH5 GT-B Right AFTER Oil + Filter Change ..

[Ledge`]

Alright lads, heres a doosey ..

Did my regular 5,000 k's oil change + filter just now, turned car on. CEL ..

Never ever came on before hand. What can cause this? I'm talking directly first turn over after the oil + filter were changed ..

Taking it in to get scanned tomorrow. Also discharging the ECU as I type this seeing if that will clear the code.

Any ideas gents?

[Rosssub]

Has the CEL stayed on? Do a manual diagnostics check and see what it is:

http://www.scoobypedia.co.uk/index.php/Knowledge/ReadingECUCodes

[Ledge`]

Error 128. Used this method: http://legacycentral.org/library/literature/codes.htm

Coolant Thermostat? .. This is so much easier to do on a Toyota!

[Rosssub]

Has the CEL gone out again?

[Ledge`]

Yes CEL is back on after having battery disconnected for 4 - 5 hours.

I got 12 long flashes, 8 short ..

[Rosssub]

Check the thermostat is working ok, but I think that CEL an be caused by the coolant temp and/or inlet air temp sensors giving false values? (big differentiation between 2 sensors trips P0128).

[Ledge`]

Thanks mate appreciate it, that's basically the conclusion I've come to after some reading.

Taking it Ray Hartley (Wellington specialist) to scan and sort for me.

My car should be fine to make the drive? About 35km's or so away?

[Joker]

I'm going to go with "yes you _should_ be fine" but keep an eye on gauges driving it that far and ear on noises etc

seems really weird

[Ledge`]

I drove from my father's workshop where I did the oil + filter change to home (about 10 - 15k's), temp sat perfectly at half way like always does.

Mystery, mystery. I can only imagine I've somehow knocked a sensor out somewhere? ..

[Ledge`]

Alright gents, answers ..

Spent a few hours this arvo at Ray Hartly's in town. Air/Fuel Ratio sensor has gone bye byes .. Not sure how I managed to get code P0128 (thermostat malfunction), but never mind. I'll trust the laptop.

$560 for a genuine replacement. Has to be unfortunately ..

Now the question is, that part was replaced 10 months ago before I bought the car by the previous owner (yes it was a genuine Subaru item) .. The sensor is still shiny, it's that new. Why would it already pack a sad and will the replacement sensor pack up after 10 months also?

[Rosssub]

Expensively interesting... Was the thermostat opening temp checked?

[Ledge`]

I don't think so. We just went with what the laptop said was throwing the code. Basically disregarded my findings with the pulsing CEL test.

The guy did test the air/fuel ratio sensor with a multi-meter and yeah, it was buggered. On the laptop all the readings connected with the sensor were all at '0' (not working), also.

Frustrating, yeap ..

[Rosssub]

Ahh I see. But yeah, bummer on the expense side.

[Ledge`]

Yeah it's rats as. Get it sussed tomorrow hopefully in the evening. Part should arrive tomorrow morning.

I'm replacing the sensor at my Fathers workshop, once the part has been replaced, will the ECU need to be reset? Will the CEL just simply turn off?

[Rosssub]

Having the battery disconnected while changing the sensor over, will reset the ECU completely. So the CEL should be gone when you reconnect and start up.

[Ledge`]

Thanks mate, really appreciate the help!

[Rosssub]

Sweet, good luck. Hopefully this one last longer than 10 months, I'm wondering if the premature AFR sensor death could be caused by tune?

[Ledge`]

I'll go right back to when I first viewed the car. The car was showing a CEL. He claimed it to be the same sensor. I asked him to go get it fixed and if it comes back with no codes then I'll buy the car, which it did.

With regards to the tune, the old owner claimed to have run it on 95. Right from the word go, I have always religiously run on BP 98. I did a few tanks on BP 98, then had the ECU reset.

Anyway, problem is fixed. New fuel/air ratio sensor has been installed (genuine Subaru part). Comparing the two, I don't think the one that broke was an original part like I was assured ..

My reasons are, the new genuine one I bought had chassis clips to clip the wire to the chassis up to the plug, where the broken one didn't, it was just cable tied with no factory mounting clips. Also, the numbers were different on both sensors. I expected them to be exactly the same. The part numbers were correct, but on the broken one there were different markings and numbers ..

Feeling a bit let down as I'm rather confident the old owner purposely did not pay big bucks for a genuine part, instead tell me otherwise.