I hope nobody mind me posting to an old thread. I too got engine code 1 on my crx.I replaced the o2 sensor and I still get code 1. I did check the voltage output from the o2 sensor and it is within spec. the question and respond to is how can you still get a bad o2 sensor code with a brand new o2 sensor.

I agree other issues that affect fuel mixture ratio could cause the Ecu to think the o2 sensor is wrong. For example I had a Mazda with a significant vacuum leak causing a lean condition, the ECU compensated by adding more fuel. The ECU reached max fuel trim and the lean condition still exists because off the vacuum leak.

I just discovered my injector seals are leaking fuel. I believe this has a similar effect on the fuel (leaning it out) so the computer compensate as much as possible but eventually reaches a limit and it concludes the o2 sensor is bad.

Regarding getting the old sensor (I'm sure this is too late for the OP but may help others reading this), break off the top of the old sensor and then use a socket wrench or use a 6 point box wrench. other option is vice grips. Before hand soak it generously with the best penetrating oil you can buy as long as practical. I sprayed mine every 10 minutes for about a couple hours. sometimes an over night soak is good. after you assist it, tap around it with a wrench.

Lastly heating it with a torch will help it come out more easily to. It really works.

if the space is really tight against the radiator, just pull the radiator, you'll get more room and can possibly get a socket on a long extension in and use an impact wrench on it...

anybody wanna chime in on the leaky fuel injector/vacuum leak theory? if like to hear your thoughts and experiences.

good luck &
thanks

 

Got engine code 1 on my CRX HF. I replaced the o2 sensor and I still get code 1. I checked the voltage output from the o2 sensor and it is within spec, so how can you still get a bad o2 sensor(code 1) with a brand new o2 sensor?

Some background info and some of my thoughts about this: 1) my injectors were leaking some fuel around the seals to the manifold. I thought perhaps there might be a small vacuum leak there that causes a lean condition, because of "unmetered air"

but since these are not mass air flow setups, a vacuum leak would just alter the MAP signal accordingly and so fuel map would be adjusted via that + o2 sensor feedback and whatever other engine signals are used to get the correct A/F ratio. However at closed throttle it probably leaked alot more air at the injector seals.

I can't honestly figure this out. Just not enough skill with EFI diagnostics. Anyone can chime in on this I would appreciate it. Thanks

 

A code 1 doesn't necessarily indicate a bad sensor, more often it tells you the sensor is doing its job and is telling you that your exhaust gasses are out of spec.


fuel injected ED's have MAP sensors that measure the vacuum at the intake manifold. If there's an air leak to the MAP sensor the sensor will read a heavier throttle condition than what you have and will richen the mix and can lead to a code 1.

Your fuel pressure regulator can also cause a code 1. You can attach a fuel pressure gauge to the service port of your fuel filter, the workshop manual mentions you should see between 35-41psi which should rise if you disconnect the vac line to your pressure regulator. If it's outside of those specs, replace the FPR.

 

 

I haven't tested the fuel pressure regulator, nor have I checked for vacuum leaks so I guess those are first steps. Right now engine not running because middle of water pump, timing belt and other maintenance. After its running, back to diagnosing these CEL (code 1) issues, I also have a bouncy idle with headlights on only.