thardie

I'm getting P0130. I replaced it with a Denso 234-4349 (Which Napa told me was the right one. They also said it was a wideband O2 sensor). It had the right harness and same color wires as the old sensor.

My OBD tool shows "No data" for that O2 sensor, although it is showing data from the O2 sensor after the cat.

So, even after replacing the sensor and clearing the code, P0130 comes back almost immediately.

I tried doing the PCM clear (confirmed with the sweeping oil pressure gauge) but while doing Drive Mode 1, I get CEL again with P0130.

Service manual says now I should replace PCM (!!!?)

Help?

Cam

iTrader: (1)

have you checked the wiring from the o2 sensor to the ecm?

dannobre

iTrader: (3)

Borrow a known good stock one and see if it works......

If it does..you know the aftermarket sensor isn't working..

If it doesn't work..then start checking wiring etc

tza0001

iTrader: (2)

+1. You might be able to find a cheap used front O2 sensor here: www.partsgroup.com
I got a rear o2 sensor for $40 from them and works fine.

thardie

I pulled the 2 pins on the ECU that come from the sensor wires, and get between 0.1V and 0.3V on the leads when I rev the engine. When I connect the 2 pins back to the ECU, and measure the sensor with it connected to the ECU, I get 0.355V exactly constantly. Seems the ECU is faulty?

I rechecked all the wires anyway for shorts between each other and shorts to the chassis, and made sure they had good continuity - All checked out.

thardie

What's the chance the original one (which is a Denso) and the new one (Denso specified part for the RX8) both don't work?

TeamRX8

iTrader: (25)

that's why I always use the OE one

just because it's the same manufacturer doesn't mean it's the same part

dannobre

iTrader: (3)

hat's why you buy a new OEM one...try Mazmart...they have them at a good price....

Or borrow one from a car that works

If they both don't work...it's not the sensor and you have to look elsewhere

thardie

Thanks for the suggestions

So, I've tried 2 sensors, and both give the same readings (and give a P0130). I've checked the readings at the wiring harness at the PCM (ECU), so I guess my ECU's faulty? Another reason I think my PCM's faulty it while diagnosing this, I got a P2112 (I'm not sure of the code from memory), but when I looked it up, it was a throttle duty cycle check failure - I couldn't control the engine with the gas pedal while this code was present. It would idle at 2000 rpm, and when pressing the gas pedal, would raise to 2100 rpm. Even if I floored it, nothing changed. After clearing that code, throttle is normal again.

Also, the weird thing with the whole problem. My OBD shows "NO DATA" for this O2 sensor. Not 0. NO DATA. I know my OBD is working, since I get data for the sensor after the cat, and in another car I have (Honda Civic) both sensors report correctly using the same tool.

dannobre

iTrader: (3)

Check the grounds for the ECU..there are a couple under the battery box area..and one right behind the ECU...and along the fender close to the firewall.

Sure your scanner works properly? Hate to start expensive repairs when the scanner is potentially the problem

You will need to take it to the dealer to get the ECU replaced anyway..you need to be able to re-program it to as built data to get it to work

The throttle thing could be a lot of things...from the MOP to the coolant temp sensor..to the ECU....good luck

thardie

So, without boring all the long road I've been on with this problem, I've now got a brand new from Mazda, PCM. The throttle problem was loose pins on the wiring harness at the PCM.

After all of this I STILL have P0130, and I've gotten new OBD software (scantool.net) which can read all the Mazda PIDS. including the current on the front oxygen sensor. It's stuck at -128ma. If I disconnect the sensor from the PCM, it stays at -128ma. Also, the Mazda official WDS system show the sensor stuck at minimum too, and P0130, so I know my OBD is working.

This is all with the new sensor. I've checked that there are no shorts with the wiring from the PCM to the connector where the oxygen sensor plugs in, and that the wiring is good.

So, do we still think it's the sensor? The only other thing I can do now is buy ANOTHER sensor (this time, maybe a Bosch) and try that, but it's another $300. I'll do it if it'll fix the problem...

thardie

This problem is finally solved. I replaced the sensor with a Bosch one, and problems are all gone. So either the Denso sensor that Denso specifies is wrong (the one mentioned in the first thread) or I got a brand new defective one. Either way, I'm never using Denso again, and let the reader of this take my experience as they wish.

TheWyvern

Resurrecting this thread to state that this part number is for the downstream O2 sensor. When used in the proper location it works fine.

TeamRX8

iTrader: (25)

that would explain the NO DATA result then ... good catch