Hi,

I'm trying to figure out this problem where my check engine light is coming on after I replaced the oxygen sensor on my car with a brand new Bosch oxygen sensor. What happens is that when I restart a fully-warm engine (eg. running errands) and drive for about 5-10 minutes, the "Check Engine" light would come on. The ECU is spitting out the code "33", which says there's a problem with the oxygen sensor circuit. I've tried resetting the ECU about 5 times, and even disconnected the battery for a day, but this problem just will not go away.

The strange thing is, I disconnected the oxygen sensor with the engine fully warmed up, expecting the "check engine" light to immediately come on, but it doesn't! So now, I'm wondering whether this should be the case where the light isn't coming on when my oxygen sensor is disconnected, or whether my ECU module may be flaky. The ohmmeter reading for the oxygen sensor (new one) checks out okay, and the voltage reading across the red and white wires on the plug checks out battery voltage, which is what it's supposed to be at.

Can anyone out there shed some light on this matter? This new oxygen sensor seemed to have solved my intermediate stalling problem that I was having with my car that I had been receiving replies from in one of my old post, but now that one problem is solved, another one has taken its place ...

-Alan

 

Sorry, forgot to mention this is an '89 Maxima, and it has the strange two-plug oxygen sensor configuration.

 

that's weird stuff, but no, a disconnected O2 sensor will not throw an ECU code. I disconnected mine once and drove 300+ miles that day, and then didn't plug it back in for almost a week and the light never came on.

 

Matt,

Thank you for the update; so I can somewhat rule out a bad ECU then ... I'm thinking about plugging my old O2 sensor back in, even though the new sensor, I think, had cured my stalling problem with the car. If the old sensor doesn't make the "Check Engine" light come on, then I'll see if I can get another oxygen sensor.

The thing that boggles my mind is that this oxygen sensor code only started coming on with the new sensor, and it only happens after the car is fully warmed up, and only when the engine is turned on again after stopping it (say, to run errands to many different stores).

Has there been any known issues with Bosch oxygen sensors on Gen3 Maximas? My Maxima is the first car that I've ever had to swap out the oxygen sensor for, and I've usually heard good stuff about Bosch sensors.

-Alan