P0133 issue with multiple O2 sensors...

[427invader]

So we are looking at an '04 Ram 1500 5.7l Hemi. For many years I have replaced B1S1 O2 sensor. So by many years I mean 12. In that time I have never replaced any of the other sensors. So for 12 years I put 1 B1S1 sensor in per year, but no others. This year I put in 2 Bosch sensors, 2 NTK sensors, and now I have a very expensive Mopar sensor in. I still get P0133 [Oxygen Sensor Circuit Slow Response (Bank 1, Sensor 1)]. So far I have done the following with the fixes required: replaced the IAT, smoke tested the intake manifold, replaced intake manifold gasket due to leak, smoke tested again, replaced the egr valve due to leak, cleaned the egr tube, voltage tested B1S1 connector to the pcm, no issues. So finally today (6/11/26) I put the Mopar O2 sensor in with no change. I still get P0133. Does this mean that I need a new PCM? If it is the PCM, where do you suggest that I get one. (I know of 2 places that I'm comfortable with, but I want your input) Also I will need a dust cap for the 2nd from the top PCM wire harness. I opened the hood and saw it hanging. I don't know why, but it needs replaced. Thank you all for your help in advance!

 

[alpinegreenneon]

You likely have a circuit code and that means a wiring problem. You can replace a thousand O2 sensors and still get the code if the sensor can't tell the PCM what's going on. Sensors communicate by wire, not bluetooth and not WiFi.
From the FSM:
POSSIBLE CAUSES
EXHAUST SYSTEM LEAK
O2 SENSOR 1/1 SIGNAL CIRCUIT SHORTED TO VOLTAGE
O2 SENSOR 1/1 RETURN CIRCUIT SHORTED TO VOLTAGE
O2 SENSOR 1/1 SIGNAL CIRCUIT SHORTED TO GROUND
O2 SENSOR 1/1 RETURN CIRCUIT SHORTED TO GROUND
O2 SENSOR 1/1 SIGNAL CIRCUIT OPEN OR HIGH RESISTANCE
O2 SENSOR 1/1 RETURN CIRCUIT OPEN OR HIGH RESISTANCE
OXYGEN SENSOR 1/1
POWERTRAIN CONTROL MODULE (PCM)

 

[427invader]

I did not use bluetooth or WiFi to test the O2 sensor wires to the PCM. They all tested good, but I was told that a failing PCM will fail them and allow the vehicle to start and run. Am I missing your point or ?

 

[alpinegreenneon]

There are you tube videos that show how to use a multimeter to test wiring for shorts to ground, shorts to voltage, and high resistance or continuity in wiring. Signals travel to and from sensor to the PCM over wires. The PCM doesn't get signals any other way. The O2 sensor does not send or receive signals by WiFi or bluetooth which is what you may be expecting by just replacing sensors without verifying the wiring. O2 voltages are low so wiring has to be perfect.

 

[427invader]

I will look some up. Thank you

alpinegreenneon!​