njmaxseltd

iTrader: (19)

I'm throwing a check engine light about once a week with 0510. The Haynes shop manual defines that code as Downstream O2 sensor maximum voltage monitor fault. As I understand, my Cali spec 99 has 4 O2's - one on each cylinder bank before the pre cats and one on each cylinder bank after the pre cats. Therefore the definition of 0510 doesn't make sense, it's not telling me which O2 is throwing the code. I have 2 downstream (after the pre cats) sensors. Are some of the codes for a Cali spec 99 defined differently, or am I just not understanding which O2 would be the downstream sensor.

Any help would be appreciated.

Kevlo911

iTrader: (36)

Diagnostic Trouble Code 0510 points to a problem with the Rear Heated Oxygen Sensor. This sensor is mounted in the exhaust stream, just downstream of the Catalytic Converter. When the two Front Heated Oxygen Sensors are operating properly the Rear Heated Oxygen Sensor is not used for engine control operation. It is used to monitor the condition of the Catalytic Converter. If either or both Front Sensors fail the Engine Control Module uses the signal from the Rear Sensor to maintain a correct fuel/air mixture.

DTC 0510 is detected when the signal from the Rear Heated Oxygen Sensor does not reach the expected maximum voltage threshold value. The possible causes include ...
- Harness or connectors (the sensor circuit is open or shorted.)
- Rear Heated Oxygen Sensor
- Fuel pressure
- Fuel injectors
- Intake air leaks

njmaxseltd

iTrader: (19)

Kevlo, thanks for that definition. I'm not sure if my cali spec has an O2 after the main cat. I have O2's after both pre cats. I guess I'll have to get the car up on the lift at work and take a good look at the exhaust system. I think I'll change the fuel filter as well, it's been 30K miles since it's been changed.

Kevlo911

iTrader: (36)

Better go with 300zx one...

njmaxseltd

iTrader: (19)

Just took a look under the car, I have TWO downstream O2 sensors, one on each cylinder bank after the pre cats. The code doesn't specify which one it is.
There is no O2 after the main cat on my car, which is the one that 0510 points to.

0510 must mean something else on my Cali Spec 99 model.

Anybody else wanna take a stab at this?

Kevlo911

iTrader: (36)

Alright, look where hte front header is. You see 3 O2 sensor conectors. You are standing in frint of hte car. One on the left--closer to timing chain cover--is teh Rear Left Bank O2. One in hte middle is hte Rear Right bank O2. So it is hte one in the middle, follow those wires and it will lead you to the sensor.

njmaxseltd

iTrader: (19)

OK so it's the right bank rear heated O2. Gotcha.
Right bank is near the fire wall or front of the car?
There's 4 o2 plugs up front on my car.

Kevlo911

iTrader: (36)

I am pretty sure hte right bank is hte firewall.

stglock

I do have a Cali Spec 99 maxima and had been getting the 0512 code which
is the downstream O2 sensor. When I looked under the car there is no O2
sensor at the CAT as others had mentioned.

I looked at the FSM, and it indicates 4 sensors, 1 each for the left and right banks
and another 2 for each downstream.

I checked my car and I COULD only find 1 O2 downstream sensor and altogether
3..

I bought the downstream sensor as indicated by SES, but the length of the wire
is short. I will probably just spliced it.

caudio51

ever solve this issue I am getting the same thing.