Younggunspaint

Check engine light comes on, code p0135 o2 sensor heater failure, replaced sensor, checked all fuses, checked relay, and checked all the wiring back to the PCM pins, and all shows good, figured its got to be a bad PCM. Replaced PCM today, had dealer reprogram immobi system, and clear codes, start the car and boom, there's my 0135 code again, I'm at a loss....
Sensor was replaced with w genuine Honda o2 sensor... What are the odds that the used PCM from a car with only 55k on it is fried too????
I'm seriously sick of this problem, I've been at it like a month.

ezone

There's a nice troubleshooting chart in the service manual. Have you followed that?

What car do you have?
Which sensor did you replace?


I have not yet seen a PCM cause this code.

Younggunspaint

It's a 2005 civic coupe 1.7 vtec (d17a2)
Changed the upstream o2 (a/f) sensor for 250$, and I have an all data account, so I've followed all the trouble shooting guides related to that code and to a/f testing.... I'm confused, and at both ends of the step by steps I've followed it says update PCM or replace with a known good PCM... So that's why I went that route.

ezone

Unplug the sensor, connect a low watt test light to the heater circuits at the harness.
Start the engine.
Does it light the test light?
(I have actually got a code to stay away using a test light LOL)

Ohm check the heater circuit in the sensor. What is the reading?

Check terminal tension of the connector female terminals.
(I just had a car from another shop, someone had stuffed something huge into the plug terminals and mangled the female terminals so they wouldn't grip, couldn't make good contact with the males.)

Younggunspaint

I checked the heater circuit and there is battery voltage across it, but I never checked the new Honda sensor... I guess I'll have to check that next...

GOATman2006

ouch

ezone

So that verifies both power and ground to the heater, right?


Look at the wire positions too.
Maybe you got one that was miswired or mispackaged.
IDK.


Check those female terminals for grip.

Younggunspaint

Ok, so should be green and white on the sensor side right?
If so that's showing open circuit... Maybe the honda sensor is a dud?
That or I'm reading this wiring diagram wrong.

ezone

Heater circuit in the sensor normally uses the same color wires. Whichever 2 are identical.

Younggunspaint

Woops blonde moment, 1.1ohm

ezone

That sounds about right to me

Younggunspaint

And so I'm back to square 1...

ezone

https://weber.instructure.com/course...ension-testing

ezone

How long does it take to turn the CEL on again after clearing the light?
A week? An hour?

60 seconds?


How about the other 2 wires of the sensor? Is there good continuity from the plug all the way to the PCM on those?

Reason I ask is, my info indicates the PCM is not actually monitoring the heater circuit itself, rather it's looking for the correct response (change in resistance as the sensor heats up) from the sensing cell portion of the sensor after the heater circuit is turned on.

Younggunspaint

15 seconds? Maybe 10?... And one of the black wires, I believe black with white stripe of the heater circuit runs direct to the 31 pin connector at the PCM.
That's where I tested it. Right at the connector. I was under the impression that it monitored voltage there. But all data has been wrong before...

ezone

Hey, um, check the heater resistance on the rear sensor.

I'm wondering if your code reading device is spitting out an incorrect code.

My info says the front sensor P0135 check is 60 seconds, but the rear sensor P0141 check is only 5 seconds and is a circuit amperage test.

nsrhonda89

You might want to check this thread out.

https://www.civicforums.com/forums/3...ensor-1-a.html