squeakywheel

Alright folks, this is my first post here and I need your help getting rid of a P0134 on my sister's Civic so it can pass emissions. Here's some background on the car:

It's an 04 EX sedan. A couple years ago she ran it out of oil which killed the engine. She took the car to some shop and they swapped the engine. I don't know much else regarding the engine swap, but last year I was doing some work on it when I noticed the green VIN tag on the back of the engine was from an 01 car. The CEL has been on for a long time, probably since the engine swap but I don't know that for sure. The code is P0134.

Here's what I've done:

The first thing I did was replace the upstream O2 sensor that was apparently faulty. I had gotten a couple of O2s from some EX Civics at a junkyard as I was trying to fix it for cheap so it can get tested for emissions asap. I don't remember what year the donor cars where, but I know one of them was pre-04 and the other probably was as well. I had installed one of the used O2s but never cleared the CEL (I didn't know how at the time). Either way, the CEL never went away and a couple months later, the car was already past due for emissions. So my sister brings the car back to me and I installed the other used O2 sensor and cleared the CEL. After about 15 minutes of driving, the CEL came back. After this, I did some research and learned that the 01-03 engines are different than the 04-05 engines, with the main difference being that the 01-03 cars had narrow band O2s and the 04-05 cars had wide band O2s. It also seemed that people were having problems with knock-off-brand sensors and given that both used O2 sensors I had tried were NTK, I decided to get the proper Denso O2. Just 2 days ago, I replaced the upstream O2 with a Denso 234-9017, the one meant for the 04-05 years. Well I cleared the CEL and it came right back after driving about 50 yards. I have confirmed that the car still has the original ECU (part number 37820-PLR-A72), and that the wiring from the O2 sensor's connector to the ECU connector is undamaged by testing resistance with a multimeter. Yesterday, I decided to check for any possible exhaust leaks before the sensor, and I immediately thought I had found the problem when I noticed the two spring bolts were a bit loose, and at least three nuts/bolts for the exhaust manifold were also loose. I looked up the torque specs and tightened everything down to spec. Then I cleared the CEL again, went for a drive, and after about 50 yards, the CEL comes back. One more thing worth noting is that two other codes appeared when the car was scanned 2 months after installing the first used O2 sensor (P1172 and P2A0), but only the P0134 has come back after I've cleared it. I think this is because I never completed a drive cycle between clearing the CEL and scanning it again, so only the P0134 comes back.

I'm not sure what to do anymore. I thought all the D17A2 engines were mechanically identical from 01-05, so it seems that in theory the wideband O2 should work well with the 04 ECU despite the 01 engine. Also, it seems odd that one of the used NTK O2s (likely pre 04) lasted the longest before triggering the CEL. I don't think it makes any sense to try a Denso 01-03 narrowband sensor at this point, but I'm open to any ideas and suggestions. I fear the only solution at this point would be another engine swap from an 04-05 car, but I really hope it will be something far easier.

Slumpertcivic

squeakywheel

I thought the Denso 234-9017 was the same exact thing as the Honda branded sensor. At least that's what I had found through some research. Many people have had success with that sensor in an 04-05, but I it seems this particular car is the exception. So I guess it's OEM or bust? Does this mean that the 01 engine in the car is mechanically identical to the 04 engine? If this is the case, then in theory the Honda branded sensor should fix the problem. What are the chances that the ECU is the culprit?

Slumpertcivic

squeakywheel

I installed an original 36531-PLR-003 Honda sensor yesterday and all is well now. I cleared the CEL and it hasn't come back after about 10 miles of driving. Thanks for the help.

GusBuz

It depends where you bought the "denso" sensor from also. Shady sellers online might sell you faulty units. I had this experience all because I didnt want to cough up the 100 bucks for a proper "Denso"