Finally got everything running great in my '03 D2. Then ... the Three Amigos returned! I hadn't seen them for a year/since replacing the ABS Shuttle Valve. Their return was uninvited.

Here's what I've got:
* My last fix was replacing both upstream O2 sensors. Installed Walker Premium. Great product. O2 sensor faults vanished. Truck suddenly ran like (almost) new.
* After several hundred miles, The Three Amigos AND Code 430 showed up, but only intermittently. Almost never with a cold engine/at start-up, but more and more consistently after 10 minutes or more of driving.
* My first suspicion is that the new upstream O2 sensors are not communicating well with the old downstream O2 sensors. I had read that, because the downstream O2 sensors absorb far less abuse than upstream, that their replacement is rarely neccessary. Thus my inaction in replacing the downstream sensors.

I appreciate your thoughts and opinions on this minor dilema. The truck runs and drives great. Just hate those dang dash lights.

 

P0430 is a cat code, probably clogged & not being effective anymore. Amigo’s wise = read the stored ABS fault codes.