Troubleshooting p0031

[ohno06gt]

Dealing with a p0031 code in a 2006 Legacy gt. It was happening intermittently for for a few weeks but now it's constant. Afr is stuck at 14.7 on accessport.  It is a denso 02 sensor that has 15k miles on it.  

I checked the resistance on the 02 sensor heater circuit and it's 6.9 ohms. The diagnostic chart said that if it's under 10 ohms the sensor is good so I'm looking elsewhere.

The 02 sensor voltage was reading around .6 on my accessport when the car was warmed up.

The chart I was following said to check the output signal from ecm while the car is idling. How exactly do I preform this? Do I unplug the connector from the ecm and check the terminals on the ecm? Back probe the connector while it's still plugged in?

Any input/advice will be appreciated. I know very little about electricity so I'm learning as I'm going along.

Thanks

[silverton]

I'd be suspect of the O2 sensor.  I've learned over the years that just because it is new, does not mean it is good.  Here are the diag steps for P0031 from the service manual.  According to this, if you checked the correct pins on the O2 sensor, it's no good.  Should be 2-3 ohms, not less than 10.

[ohno06gt]

Thanks man, I must have been looking at the wrong troubleshooting chart.  It started working again for a 5 mile drive, when I restarted it stopped working.

 

Probably going to order the sensor today.  Just trying to decide if I should get another Denso or an AEM wideband.

[silverton]

Try Delphi or Bosch.

[m sprank]

They all use the same sensor. Pooh happens.  If it is warrant-able, just get a free replacement.  I used to buy widebands by the dozen.  You would be amazed how fast some failed on the dyno.  Some lasted 1 year, some lasted 1 pull.