O2 sensor readings - help with diagnosis?

[r00x]

I've been examining the output from the O2 sensors on my Puma (there are two), just want to get an idea if they're correct.

My equipment (a cheap bluetooth OBD reader and Torque for Android) reports four voltages for the O2 sensors. There appears to be bank 1, sensor 1 & 2, and bank 2, sensor 1 & 2.

When sat idling, the voltages reported were:

Bank 1 Sensor 1: anything from 0.05 to 0.9V (big random oscillation every second or so)

Bank 1 Sensor 2: 0.8V (steady)

Bank 2 Sensor 1: 1.3V (steady)

Bank 2 Sensor 2: 0.0V (steady)

Does this sound about right? I don't think Bank 1 Sensor 1 should be oscillating (at all). Has one/both of the O2 sensors failed? Why is Bank 2 Sensor 2 0.0v?

Which sensor corresponds to which bank - is Bank 1 the upstream sensor before the cat?

 

[johnnyd]

Bank one is in the exhaust manifold and bank 2 is after the cat.
I'd replace bank 1 pal loads of people seem to have problems with it, I did myself

 

[johnnyd]

^ never actually read the first part of what you said if you scan the vehicle if it doesn't register a problem then it's probably fine
After all if it ain't broke, don't fix it

 

[cletus100]

I've been examining the output from the O2 sensors on my Puma (there are two), just want to get an idea if they're correct.

My equipment (a cheap bluetooth OBD reader and Torque for Android) reports four voltages for the O2 sensors. There appears to be bank 1, sensor 1 & 2, and bank 2, sensor 1 & 2.

When sat idling, the voltages reported were:

Bank 1 Sensor 1: anything from 0.05 to 0.9V (big random oscillation every second or so)

Bank 1 Sensor 2: 0.8V (steady)

Bank 2 Sensor 1: 1.3V (steady)

Bank 2 Sensor 2: 0.0V (steady)

Does this sound about right? I don't think Bank 1 Sensor 1 should be oscillating (at all). Has one/both of the O2 sensors failed? Why is Bank 2 Sensor 2 0.0v?

Which sensor corresponds to which bank - is Bank 1 the upstream sensor before the cat?

The reason you get bank 1 and bank 2 is for V engines, don't forget your scanner is generic, ignore bank 2 this is why there's no change on them. Bank 1 sensor 1 is the upstream HEGO (precat) bank 1 sensor 2 is the downstream HEGO (postcat) the readings for these are accurate sensor 1 voltage is the switching between rich and lean mixture as the engine management tries to maintain the correct mixture. If sensor 2 followed this then the Cat. is no good. Sensor 2 voltage will move if you rev the engine hard then let it drop to idle but it won't jump about like sensor 1.

 

[r00x]

Excellent, thanks for the information. I was indeed only testing at idle, should've puttered around a bit. Is the voltage swing on sensor 1 OK? As I understand, the ECU deliberately oscillates mixture back and forth and this is normal functionality?

I'm trying to get to the bottom of some interesting engine behaviour (high fuel consumption, doesn't feel like it's pulling quite enough either, seems ever so slightly inconsistent, also feels like it's missing the occasional ignition cycle accelerating through 1100-2000K RPM) it was the high consumption that made me wonder about the sensors.