My 2008 Grand Caravan 3.3 FF is calling out P0135 and P0141. I took it to the dealer and they diagnosed it as a short in the upstream oxygen sensor heater and a bad downstream sensor. I have replaced both sensors (Bosch) and the codes come back. These codes popped up after a dead battery replacement. I have read that the sensors from Bosch can frequently be bad. Before I go purchase Mopar sensors I want to ensure I have missed something basic like a blown fuse. I have checked every fuse in the fuse panel and not found and blown fuses. Is there a fuse or relay between the PCM or battery and the oxygen sensors? If so where is it? Any other ideas on how to pinpoint this?

 

I have also read that Chrysler vans "don't like" Bosch O2 sensors. The older generation vans did come with Denso brand sensors and most people recommend replacing with the same.

But the original upstream O2 sensor on my '09 Grand Caravan was a Bosch sensor, I replaced it with a Bosch from a local auto parts store, it's been working fine. The replacement sensor looked identical to the original, right down to the Chrysler part number marking.

I haven't looked at the downstream O2 sensor yet, so I don't know what brand it is.

 

Looking at a wire diagram there's no fuses or relays. Seems against the odds both heaters die at the same time. Might want to verify the PCM is supplying the voltage to the heaters and both grounds are good. Pin 2 is heater power pin 1 is ground on both sensors.