BlueKat

About 2 months ago I bought a 2004 D17A2 (Canadian 2-door Si coupe) with the CEL on and an exhaust leak. Only code on the OBD-2 was P0134 -- simle fix I thought ... I was wrong!

First I replaced the exhaust gasket, then erased the code and it came back within a minute. Next, I installed a new O2 sensor (DENSO universal 4 wire) making sure the wires were correct from the sensor to the OEM connector. Still throwing P0134 after 2 minutes of driving! I bought the shop manual. Even though I don't have the P0135 code, I went through the troubleshooting algorithm suggested for the case in which both p0134 and p0135 come up and came across something weird -- the voltage across pins 3-4 on the male connector side of the primary O2 sensor (A/F sensor) had a voltage of 9.6 (batt voltage was 12 something). At that point, the book recommends having the ECM updated.

I took it to the Honda dealership. It cost $74.39 for the ECM/PCM update. Driving away, the CEL came back on within 5 minutes. I re-scanned when I got to my shop and still have P0134.

I visually checked all the fuses after reading this (but I don't know which fuse to investigate).

Other info: I tried adding AmsOil P.I. (gasoline additive concentrate) as recommended by a parts guy *and* a tech at the Honda dealership after telling my story ... obviously no dice.

*after* I bought the car, I upgraded the exhaust with a Megan header and MagnaFlow cat-back. I even tried clearing the P0134 code and trying the O2 sensor in the header (with the stock primary HO2S boss plugged off). I also added an AEM cold air intake.

I'm looking for ideas or knowledge about what has worked from people who have experienced my problem or people who know this car better than I do. Apparently nobody at the Honda dealership can fix it. I was told about a "similar" TSB on the '05 Si, but that was for the secondary sensor.

Any help would be appreciated. I visually checked the wiring harness from the O2 sensor connector back to the fusebox and can't see anything abnormal. When I took out the air cleaner housing and resonator, everything looked original except the PCV valve and hose. The car has 213,000 kms.

I've read the posts that advise using the OE sensor, but I think I have a problem with too much resistance between pins 3-4 on the connector side (so paying $260 for a sensor could be a waste). I should also add that the shop manual states "resistance between 1 - 10 ohm? OK" but it had been revised. Anything more than 3 ohm (or 3. something, I can't remember exactly) suggests a problem.

BlueKat

For those who may benefit, I fixed the problem by installing a Honda LAF sensor. O2 sensors don't work in '04/'05 Civics. Lesson learned.

It Wasn't Me

Thanks for the update! I'm sure the info will save someone a future headache. Provided they actually search before making a thread, that is.

chivalya

I will definitely try that. Thanks!

TLDCC

Hello BlueKat, would you mind letting us know what A/F sensor, maybe the part number that you used to fix this problem? Thanks a lot!

BlueKat

Honda part no. 36531-PZA-A01

lazlong

Those are listed for Civic Hybrids only.

TLDCC

Big thanks BlueKat!