Rich/Lean codes


adamputz

15+ Year Member

Joined
Jan 6, 2009
Messages
16
Points
3,101
Vehicle Year
1993
Transmission
Manual
I'm getting all these codes on my truck, it feels like its running really rich and dogging it on the highway. I'm not sure where to start looking since it's throwing both lean and rich codes. Could it be something electrical? any advice or idea would be great.

522 - (O) Park/Neutral Position (PNP) or Clutch Pedal Position (CPP) circuit fault - PNP transmission MLP sensor out of range in park - Transmissions

172 - (R,M) Oxygen sensor not switching - system is or was lean - Single, Right or Rear HO2S - Fuel control

173 - (R,M) Oxygen sensor not switching - system is or was rich - Single, Right or Rear HO2S - Fuel control

176 - (M) Oxygen sensor not switching - system is or was lean Left or Front HO2S - Fuel control

177 - (M) Oxygen sensor not switching - system was rich Left or Front HO2S - Fuel control
 
Sounds like a bad neutral safety switch and perhaps the Fuel Pressure Regulator. Pull its vaccum hose off and smell for raw gas. If you smell gas, replace it. Hard to imagine both O2 sensors going bad at once....check fuse 18 (HEGO).
 
I'll check the fuse for it. Sorry I forgot to mention I already changed the fuel pressure regulator, fuel filter, 2 of the O2 sensors, the IAT sensor, and a bad injector (the intake manifold gaskets were also replaced).
 
check for any penched wires and connector corrosion, it sounds like you got lazy o2's but i would expect them to be good being new and all
 

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