O2 Sensor showing 1.33 Volts

[sagalasan]

Hi, I recently bought a 98 Eclipse GST about 2 weeks ago with a rough idle problem. The downstream O2 sensor wires are cut for some reason and the upstream O2 sensor is plugged in.

When I read the data from the ECU I see that O2 Sensor 1 Bank 1 says 1.33 volts consistently even after long warm up and a long cruise. I was wondering if this has anything to do with the rough idle.

Also I tested the voltage of the O2 sensor unplugged with a voltmeter and it was oscillating between about .1 and .5 volts, so I am assuming the O2 sensor is good and something is happening in the ECU or wiring.

P.S. I can't start the car at the moment because I'm replacing the timing belt, rebuilding the turbo, and waiting for a crankshaft sprocket to come in because it had a tooth missing.

 

[Lofty]

O2 sensors should never show stable voltage.


I would double check the wiring. Take the secondary o2 sensor and plug it in and see if that changes anything. I would not assume it automatically works because it is seeing volatage, but you probably have to wait until your car is running. Sounds like either wiring, or the sensor itself, and then would be O2. What is the coolant temp looking like? It is possible you blew your sensor ground out of the ECU. Which will have a consistent -133 (ish) temp on the coolant. If you have a way to log this, it would tell you so.


Good luck.

 

[sagalasan]

Ok, so I soldered the wires back together for the rear o2 sensor and put everything back together. The coolant temperature is showing normal readings but the front o2 sensor still shows 1.3 volts consistently even when unplugged. The rear o2 still says 0 volts. It still idles really rough and then dies after about 30 seconds.

 

[sagalasan]

Well I figured out why the car kept dying. It turned out to be caused by the bov being stuck open.

As for the o2 sensor voltage, the previous owner decided it would be a good idea to switch the brake booster and o2 sensor connections. The o2 sensor now properly cycles and the ecu stays in closed loop mode.