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B1S2 O2 voltage erratic

2K views 5 replies 2 participants last post by  98zheadsncam 
#1 ·
Ok, my first post on this forum. I'm mainly a GM lsx person, however, I own a Rio as well, mainly for the gas mileage. Lol. At any rate, I ran a scan on the car the other day, and the voltage on B1S2 wasn't oscillating normally. It would stick at .700ish mv and flat line. I figured it was the sensor (120,000+miles, so it was expected). I replaced the sensor, and it's still giving the same erratic readings. (Between .400 and 420 mv and back and forth when I started it just now). Any suggestions?

Thanks!
 
#3 ·
I hooked the scanner up because the car started running rough and missing. After turning off the motor and starting it back up again, it ran ok, so I figured maybe the MAF. Saw the voltage on the post cat sensor and figured that was the problem.

The only DTC that's been set is P0447 - evaporative emisson system vent circuit open. It's been like that for several years. Never seemed to affect anything.

I guess I'll see if I can find any vacuum leaks, but I'm thinking this has got to be a sensor related issue.
 
#5 ·
I didn't actually see it misfiring on the scanner, because the scanner wasn't hooked up while it was running rough. It felt like one of the plug wires was unhooked when it was acting up, though. One thing I noticed with the last scan was the TPS showed like 18 percent at idle. The car was running fine at that point, however. Maybe I should try resetting the TPS...or maybe the sensor is bad. I would have thought the ecm seeing 18 percent throttle at idle would automatically translate to the motor running rough, though.
 
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