Hey all. I have a 2003 Dakota quad cab 3.9l v6. I was getting o2 sensor codes, and after looking at the state of them (they looked original) I replaced the upstream and downstream o2 sensors. I've read in other forums that bank 1 means drivers side, bank 2 means passenger side, sensor 1 upstream, sensor 2 downstream. If this is correct, the sensors I replaced ( the only o2 sensors there are on my truck) are bank 2 sensor 1 and bank 2 sensor 2. I'm now getting codes P0031 and P0037, which relate to Bank 1 heater circuits, and my truck does not have o2 sensors on bank 1. Could this be a ecu problem?

 

now i see i'm throwing a p0132 code as well. all of these codes refer to o2 sensors that don't even exist on my truck. what gives?

 

Just incase it might help someone in the future...found fuse U in PDC under hood was blown. Must have shorted out a wire during install. P0031, P0037, P0132 all disappeared after fuse replacement, CEL light is OFF, and truck is running great!

 

I'm having the same problem on my 2002 3.9l, however I don't see any under hood fuses related to the O2 sensor or labeled "U". Would they really change the wiring harness from 2002 - 2003?

 

Make that 2001-2003, it was fuse U then as well, in the PDC.

Not sure on your 2002, in 2001 there is a vertical row of 4 fuses just above two rows of horizontal fuses. "U" is the right most fuse.

 

Thanks. Found it. Fuse had been completely removed (!) which is why I missed it when looking previously. Lights are off and all is well!