View Full Version : 07 impreza P0131 trouble tree
Cavemanrjc
05-09-2010, 10:19 AM
Diagnostic trouble tree P0131
1- Check front O2/afr sensor connector and coupling for water intrusion
yes - completely dry out and pack with dielectric grease
no- go to step 2
2- Check harness between ECM and Front oxygen/AF ratio sensor.
-Turn ignition switch off.
-Disconnect harness from ecm and A/F sensor.
-Measure resistance between ecm plug pins #8 & #9 to chaise ground
-Is the resistance greater them 1M ohms ?
no - repair short in circuit
yes- go to step3
3-Check Poor Contact in A/f sensor plug
-Is there poor contact in the connector?
with a fine paper clip check to see if the female side terminals have drag on the paper clip.
no poor contact- repair terminals
yes good contact- replace a/f sensor
Direct from Snap-On Shopkey5 also know as Mitchell on demand
Hope this helps
Sir-knight
05-09-2010, 11:33 AM
thanks, which pins are the ground pins? in the meantime... will reset ecu and go to canadian tire to pick up grease and volt meter
Cavemanrjc
05-09-2010, 12:09 PM
Pin 8&9 are the first 2 pins in the second row down , the first full row in the connector # b135
I miss quoted but edited the tree
just have to check for continuity to ground on the 2 pins
Good luck I hope its a wiring issue as the A/F ratio sensors are not cheep, and you can not use a universal O2 sensor ether.
Sir-knight
05-09-2010, 04:07 PM
applied grease, re soldered all wiring with hotter iron this time so it was done right, gave a pull, didn't come apart. CEL came back within about 5 km. Wiring harness on the car side has not changed at all so it should work fine, I'm thinking the front o2 is pooched though been reading they don't usually go bad... so maybe it has to do with the way I extended it. I wish there were an extension cable for it like the rear o2... someone makes one for that... else I could cut the corresponding plug off the harness of a wrecked car and make one, but I don't think a scrapper would really like me doing that to a harness.
STeveD
05-09-2010, 11:17 PM
The sensors can fail prematurely, just like any manufactured part. If you can show that you've analyzed everything else from the troubleshooting tree, take it back to the shop you bought it from.
MANL?
Sir-knight
05-10-2010, 12:56 PM
sensor was oem from my stock system, can't take it back on my non oem exaust with wire slipced in.
Sir-knight
05-10-2010, 12:58 PM
on that note, I am in urgent need of a front o2 working or non from a n/a 06-07 4 wire 6 pin connector to use the wiring as a donor for a new harness extension i'm making for the new sensor I just ordered
Sir-knight
05-25-2010, 12:53 AM
STeveD
05-25-2010, 07:39 AM
Sir-knight
05-25-2010, 09:10 AM
Cavemanrjc
05-25-2010, 12:42 PM
Sir-knight
05-26-2010, 08:21 AM
valheru
05-26-2010, 08:29 AM
Sir-knight
05-26-2010, 07:44 PM
beat on it a bit today, seems to be just fine now. Hopefully the sensor lasts a good long while.
I'd be more comfortable if I were able to log the car and get valuable info... like the egt as it hits the front sensor and compare it to stock, but I think I'd need a true wideband to get that data.
Cavemanrjc
05-26-2010, 10:16 PM
If you have the old sensor and a body side plug i can make you an extension at picton
Ill have all my stuff with me to do it
As I drive a dmod, tools are an essential part of the stuff i bring with me
there more then likely is a specific MAF cleaner (waste of $$$) bc works fine and is widely excepted by driveabuility techs, key thing is what ever you use make sure it wont leave a residue
Sir-knight
05-27-2010, 08:26 AM
I have both plugs but no wire long enough to drop in, the wire that's left on both plugs might be long enough to splice from if that's what you're thinking, but I was going to look for the actual pins from inside the connectors. I'll bring them to picton though since the dealers don't seem to have what I need to do this.
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