I am an ASE Master Tech and I'm stumped. I have an 03 Ram 1500 with the 5.7 hemi in it. The engine was replaced at 180k with a salvage unit with 57k on it. The truck odo is 210k now. The Pcm was replaced and flashed by the local dealer. The truck came back with a P0132 (Os B1S1 voltage too hi (above 3.9V for 30sec). I found melted wires at the B1S1 sensor and rewired the whole mess right to the Pcm. The truck now has a P0171 Sys too lean code and the B1S1 voltage is now too low (drops to 1.3 to 1.8V under 2500 Rpm load, setting the code. The B1S2 (Truck is Calif. emissions compliant and only has 2 O2s) reads at 3.4V steady and has the heater on 100%. The front O2 Htr comes on and off, never more than 50%. The P2299 is the computer seeing the brakes on during an accleration away from a stop. This is not my main concern tho. The truck has new plugs and wires (yes I routed them per Dodge's tangled mess instructions), a new cam sensor, a new B1S1 O2 (the second one now) and i can not find any vaccuum leaks. The truck will occasionally take on a lopeing idle and seems to be trying to find a happy idle but sometimes it runs just fine. Could the Pcm be seeing too hi of a voltage on B1S2 in relation to the B1S1 voltage, and in effect trying to compensate for erroneous data by leaning out the fuel trim? Any help here would be greatly appreciated from one and all! I hate letting these things beat me!!!
Brad

 

Hi there,

How did you check for Vacuum leaks? Propane is the best way.

Also, take alook at the exhaust manifold and pipe. If you have a crack before the o2 sensor, there will be excess o2 flowing past the o2 sensor, giving you that lean code.

Now i thought all o2 sensors worked on a 1vREF? or am i reading your post wrong?

 

The new dodge ecu systems are a bit different than the old style pcm. They are on average 1 volt higher than previous systems. The difference is just in how the computer reads the voltage. So yes, its still one volt or less, but the ecu shows it at about 2.5 volts. Its stupid, I know, but thats what the engineers have done.... I haven't had the truck back in the shop since rewiring the o2 sensor (which brought the signal voltage down from 3.9 volts, the reason the eng light was on, to less than one volt, which is too low and set the po171 code that I'm now dealing with).