Codes P0171, P0172

[ehnco]

96 Explorer (pushrod v-6). 104,000 relatively trouble free (and well maintained) miles. Recently had a CEL code P0401 that turned out to be the DPFE sensor. The other codes that showed up are P0171 and P0172 for system lean (both banks). AutoZone cleared the codes for me. After clearing the codes, the CEL came back on after about drive cycles. I also have what sounds like an exhaust leak on the passenger side (feels like it's forward of the gas pedal inside the vehicle). Would an exhaust leak trigger codes for system lean ? What should I look for. O2 sensors are original, never cleaned the MAF, and PCV has about 30,000 on it. It runs beautifully with a very rare occurrence of rough idle. (warm or hot). Any ideas ??

 

[Blee1099]

Originally posted by ehnco
96 Explorer (pushrod v-6). 104,000 relatively trouble free (and well maintained) miles. Recently had a CEL code P0401 that turned out to be the DPFE sensor. The other codes that showed up are P0171 and P0172 for system lean (both banks). AutoZone cleared the codes for me. After clearing the codes, the CEL came back on after about drive cycles. I also have what sounds like an exhaust leak on the passenger side (feels like it's forward of the gas pedal inside the vehicle). Would an exhaust leak trigger codes for system lean ? What should I look for. O2 sensors are original, never cleaned the MAF, and PCV has about 30,000 on it. It runs beautifully with a very rare occurrence of rough idle. (warm or hot). Any ideas ??

Are you sure of P0171 & P0172? Reason why is they both refer to bank 1 and 171 is too lean and 172 is too rich.

 

[Alec]

If one O2 triggers both lean and rich codes, it could be a bad sensor.

 

[ehnco]

Whoops.... that should have been P0171,P0174.

The codes are: P0171,P0174. Lean condition both banks. Sorry........

 

[Blee1099]

Re: Whoops.... that should have been P0171,P0174.

Originally posted by ehnco
The codes are: P0171,P0174. Lean condition both banks. Sorry........

Thats both banks being lean. Probably bad 02 sensors. Given the mileage, I would assume it is. I don't know what the life expectancy of a 02 sensor is.

 

[Alec]

Both lean could also be a clogged fuel filter, bad FPR, or another problem with the fuel system.

It's unlikely the exhaust leak is causing the codes, but that should be fixed too.

 

[Blee1099]

Originally posted by Alec
Both lean could also be a clogged fuel filter, bad FPR, or another problem with the fuel system.

It's unlikely the exhaust leak is causing the codes, but that should be fixed too.

You are right Alec, it could be a number of things, I've always thought that when a 02 sensor goes bad it will throw a specific code in the P0130-P0167 code bank which pertain specifically for o2 sensors.

 

[Alec]

However, the fuel system components don't have codes themselves and a lean condition can be indicative of a fuel blockage.

 

[Blee1099]

I just went by what my AutoTap scanner's book says. It says that the OBDII can interpret fuel rail, composition, and temperature. Was looking forever for a good one that could interpret transmission, airbag, ABS codes and finally got hooked on this one due to the price.