1 code left.. o2 sensor p0134

[mastamoon]

Hey All,

Well I have worked through a few CEL's now since getting this truck a few months ago. Right now I have 1 left that im trying to figure out before I go out and buy a part. Just gotta get this thing through inspection so I can work on fixing all the other stuff.

P0134 HO2S1 (B1) High Voltage

When looking at this sensor in realtime with Torque (android app), I can see some activity.. but its mostly just either 0 volts or 1.27 volts. Checked out the FSM and tried to do some troubleshooting. Found the plug and checked that first, looks ok. I did the ohm measure between pins 1 and 3 and got something slightly higher than the 2.3 to 4.3 spec the manual shows, but it says "77 F" there and the engine might have been warmer than that so I dont know if a 5.x reading would be ok at a higher temp? There was also no continuity between 1 and 2 and 2 and 3.

The other tests require checking the wires between the plug and the ECM. Im not sure how you are supposed to do this with normal length leads and I was hoping to not have to dig the ECM out of from behind the center console.

Given the results I got testing the o2 side and the readings from my obdII scanner/reader/logger, is it safe to say its 'likely' a bad/going o2 sensor, or could there really be an issue between the o2 sensor and the ECM?

[mastamoon]

Not sure why it shows the code meaning No Activity, but the FSM says its High Voltage.

[mastamoon]

And just as a note, I was also getting a P0171 (System too Lean (bank 1)) before but that seems to have been replaced by this code.. is that possibly an indication that the sensor just has finally kicked the bucket?

[mastamoon]

Bumpies..

Sorry to bump.. but I need to figure this out soon since my rejected sticker is about to expire. I guess I'm going to throw a new O2 sensor at it and see what happens. Not quite sure how to test the wires from the ecu to the plug using a multimeter with short wires.

[rgk]

You mean to test resistance? Find some long, thin wire and securely wrap it around your multimeter leads. Then probe with the additional wire.

[mastamoon]

You mean to test resistance? Find some long, thin wire and securely wrap it around your multimeter leads. Then probe with the additional wire.

I would assume that would throw the readings off a bit? Probably would work fine for continuity though. Looks like you have to take apart half the passenger side dash to get to the ecu..

[rgk]

My 2002 has it just under the steering wheel, not too terribly difficult to access. I would imagine it would be the same for your 2001.

[attofarad]

My 2002 has it just under the steering wheel, not too terribly difficult to access. I would imagine it would be the same for your 2001.

Isn't bank 1 on the passenger (right) side?

[attofarad]

Bumpies..

I guess I'm going to throw a new O2 sensor at it and see what happens.

I don't know about the 2001 Pathfinder, but the 2001 QX4 did a change in the O2 sensor, part way through the year. I don't know that the sensor itself changed, but the connector did. IIRC, there was a green connector (earlier?) and a grey connector (or maybe that is just for the Bosch replacement parts.) Look at yours, and make sure the part you buy will connect.

[rgk]

Looks like you have to take apart half the passenger side dash to get to the ecu..

The ECU is under the steering wheel.