Contour Enthusiasts Group Archives Forums General Troubleshooting Blowing O2 sensor fuse

CEL came on yesterday, pulled codes and found all 4 O2 sensors and all 4 heater circuits reporting for duty. Found F13 underhood was blown, I replaced it and it blew again... supposedly there is a O2 Heater relay under the dash.... don't know if this might be the problem, but a bad relay causing a dead short that can blow a 20A fuse?

- any one have any thoughts?

2000 SVT- 59,000 miles and counting

edit: Check your PM.

Check this thread click for a suggested way of proceeding.

p.s. Not familiar with relay you mention, might be unique to 2000 model. Does your owner's manual confirm its existence on the fuse charts?

The owners manual lists it as a relay outside of a box, near the PCM... I found two relays under there, but neither is wired to anything matching what the Haynes manual shows (no surprise) I really think its a short in a wire somewhere... but I need a better O2 sensor system diagram...

Well my Haynes doesn't show '97-'98 accurately, so I wouldn't rely on it.

As you have already suggested, doubtful relay source of short. Previous models had PCM controlling heater circuits directly. Sounds like isolating relay added to reduce current PCM has to handle. Presumably the fpour sensors' heaters are now fed from this relay's contact.