Well, guys, with 110k on the odo. my quest continues to fix my car. Just 3 months ago i replaced the 1st Oxygen sensor as i was getting a "Main catalyst below minimum threshold" CEL. I knew the cat was fine as it was replaced with a carsound unit. So a few days ago i was getting some exhaust work done and a CEL came on. My handy-dandy mech with a kick @ss scan tool read a bad 02 (bank 1) a first for me but suprising since i replaced it 3 months ago. His scan tool is able to display real time readings as the car was on so we scrolled down the the O2 sensor output voltages and low and behold the 1st O2 output voltage is stuck a 4.6v. I reved her up and it was still stuck at 4.6v. 4.6v no matter what. For the record though the 2nd O2 was working as the voltage was fluctuating according to engine speed. Luckily the O2 sensor i bought 3 months ago (Bosch Universal) is still under warranty (expires in 3 days )and i ordered an OE replacement this time. Any Idea how a O2 sensor would get "stuck" at a specific voltage? Is 4.6 a maximum voltage for this kind of sensor? If so you all think it blew and is reading Infinite resistance therfore throwing out max. voltage? I just don't know much of the electrical make-up of an O2 sensor.

 

4.6v sounds like the ECU is using source voltage in place of bad info from the sensor. Did you actually get under the car and see if this value was correct? Most likely this is not the case. Whenever sensors go bad the ECU compensates by applying source voltage(5V) and then using a good value in its place. This was meant to get you to the next available repair facility not to drive around daily as your car will now not enter closed loop meaning it is stuck dead rich until you fix this. If anyone knows if the info i have shared is wrong please correct me.

 

I hate to say it, but it sounds like you installed the wrong o2 sensor.

The #1 02 sensor is heated. It accepts a 5V heater voltage, and then the 0-1V signal voltage, and a ground. The #2 o2 sensor is NON HEATED. It cannot accept the 5V heater voltage, and it will return a 5V (or close to it) voltage if used as a #1 o2 sensor....

[ January 18, 2003, 06:45 PM: Message edited by: Random ]

 

Well, Tony, i used a Universal Bosch and it worked fine for 3 months. Are there such things as a universal "front/rear"? Autozone didn't mention it. Anyhow, i bought a Bosch OE replacement one and installed it last week. So far so good unit I got another CEL last night. I think it was my fault though...I just came home from my girlfriend's house and was idling in my drive way and noticed my idle would drop about 300 rpms when i'd switch my lights on and off and the engine would feel like it would struggle to stay alive for that brief sec. It was about 15 degrees farenheit last night too. A 300 rpm drop i thought was pretty big, since it made my car shake when i'd flick the lights on. It'd idle around 800 ( i have a 5speed) and drop to 500 for a sec. when i'd switch on the lights then pick back up. So then i started to blip the throttle to see how far it would drop on its way down. After flicking the lights on/off and bliping the throttle for 5 min. i got a CEL exactly when the engine dropped to 500 rpms (every time it'd drop to 500 i get the shaking a the engine felt like it was about to die for that breif sec.). I'm gonna go get the code checked out today. I'll post what it is when i get back. sad.gif

Okay well, the verdict is a P1123 code. I think the engine just dropped to low on the idle and screwed itself.

[ January 22, 2003, 08:41 AM: Message edited by: Koreandude ]

 

No, there is no such thing as a "universal" o2 sensor.

Our front o2 sensors are heated, the rear is non heated. If you install a non-heated sensor in a heated sensor wiring harness, it will eventually burn out and throw a CEL.

When buying o2 sensors, ALWAYS and ONLY use the OEM sensors from the dealer. Unless you can verify that the part number on the dealer part is the same as the part number from the other shop.