2004 Honda CR-V - P0134

The Tech did state that he ran through the entire Honda flow chart procedure and it passed all tests leading to the sensor. Which is what I did and that's why I originally replaced the senor as well (with a Denso aftermarket sensor). I won't have the car back until Monday as that's when I get the parts in, so you have some time for research. I've got to say, you always hear the stories about that one car that kicks your butt and this has been mine to date. I've got about 6 hours of diagnoses time, not to mention all the outside forum time and customer interactions, etc...

Gotcha, I'll let you know what I find.

Dunno if I got back to you soon enough. :blush: There are codes that cover shorts and opens. P2238, P2252, P1158 and P1159.

There's no chance that the sensor connectors got mixed around, right? Between downstream and upstream. That's the only other thing I can think of that'd cause issues.

There was a mention of battery voltage at both heater wires, back probing, with the sensor plugged in. Voltage after a load means high resistance in the ground circuit. Unless I misread what was posted, does the heater have an open ground?

I think he did mention that? But he also said he connected a test light across the heater circuit and got a bright light.

Thanks for bumping this thread, though! I always meant to follow up with 69Camaro on how the OE sensor turned out.

Hi there, looking for an update on this situation? I have a P0134 code on a 2004 Honda CR-V that came on immediately after replacing the starter (or couple days later) where I went from the top (removed TB and IAC lines).

I don't have a nice scan tool (just torque app on my phone) and was getting no volt reading through the scan tool for the upstream o2 sensor (at all RPM's). Seems like straight forward bad sensor-- ordered honda OEM sensor but just wanted to know what ended up happening with yours?

I am wondering about what the final outcome was on the 2003 CRV P0134 error. I am having the same problem with my daughter's 2003 CRV and I have a 2002 CRV that does not have the issue nor does it have any codes.I have been a YouTube subscriber of yours for years and have been working on Hondas (have 9 old ones) for about 15 years. l am retired now from fixing Radiology systems for 45 years, so I have a lot of experience with CAN technology, sensors, pot/encoder problems and grounding and floating wiring issues. Just looking for a couple of ideas of what you found. I hail from Ligonier, Pa. Love your approach to solving problems. Thanks in advance, Denny

I too, would like to know how this turns out. I've been working on a 2003 CR-V LX with the P0134 code. Swapped the air fuel ratio sensor relay and sensor with known good ones. Just not sure if the ECU/PCM needs changed or updated and how much something like that would cost at the dealer.

The engine light/code always reappears shortly after resetting the computer.

I've reached out to 69Camaro for any follow up they can offer.

69Camaro was kind enough to e-mail me back. Turns out, the owner of his '04 CR-V is still fighting the same code. Multiple sensors. It's at the dealer again right now.

If it's any help, I was able to dig this out of SI:



I really wish I'd had this when the thread started. :silly: Required reading for anyone battling this code. Here's the crucial bit:

Malfunction determination 1
The A/F sensor internal resistance value is 40 Ω or more for at least 90 seconds right after the engine starts.
Malfunction determination 2
The A/F sensor internal resistance value is 40 Ω or more for at least 16 seconds.

The way I understand it, sensor resistance is a product of the sensor, the wiring, the heater, the air/fuel ratio and the PCM (which measures the resistance). I'm starting to wonder if the sensor side check for 1.8V and 2.2V isn't good enough...

The 2.7 Volts that you saw on the ground control wire( I think is wrong) it should close to zero hardness unplug.

If you plugged in the A/F sensor, you should get battery voltage coming across from other + wire


I have a similar issue w/ P0134 code and will be following back to computer but before replacing I need to check grounds, power to it.

AF pegged. What does the secondary look like? Pegged opposite? Pegged similar? Also, did anyone attempt to force lean/rich with a deliberate air leak and injecting a combustible in the intake?

This is a stock ecm setup? Are you running KPro?

Today, I did some more digging and found some interesting results.

AFR unplug, Heater+= 12.5 volts Heater / ground - = 2.47 volts

Removed AFR Relay Heater + = 0.00 volts Heater/ ground - = 0.00 volts

The current from the hot side of the heater is making it to the ground cable some where.

Great video from Dan describes the operation and testing of a AFR.

In Honda's, tight exhaust valves can also caused a problem.