P0138 AND P0171

[Exos]

My MIL came on yesterday and I've got two codes

P0171
Fuel System Lean (Bank 1) (The actual MIL code)

P0138
O2 (B1 S2) Circuit Short to Voltage (pending code)

Besides the downstream 02 sensor gone bad, what else could it be/should I check?

Freeze Frame Information
Parameter Description Value
DTC for which Freeze Frame was Stored P0171
Fuel System 1 Status Closed Loop
Fuel System 2 Status Not Supported
Calculated LOAD Value 19.22 %
Engine Coolant Temp 199.40 °F
Short Term Fuel Trim - Bank 1 32.81 %
Long Term Fuel Trim - Bank 1 32.03 %
Intake Manifold Absolute Pressure 12.14 inHg
Engine RPM 1,408.00 rpm
Vehicle Speed Sensor 11.81 mph

[lafrad]

This would actually point at your UPSTREAM O2 sensor.. the one closest to the header.

Looks like your fuel trims are fully maxed out... +30%. YOu either have a melted/burned through wire there, you need to get bigger injectors, or you have to start working with a map adjuster to get more fuel in at that load point.

[Exos]

B1 S2, should be the downstream sensor, or what am I missing?...

This is not a stroker, it's a pre-stroker that is acting up on me 4 days before swap.

Something that might, just might be related : My water pump is toast and I'm leaking coolant from it. I had to put back half a gallon today. Maybe the coolant sensor is part of this? I'll check my o2 sensors tomorrow for damaged wires.

[Biggrnjeep97]

An unaltered 4.0l should not have that much ST FT/LT FT(+30%). Your computer is trying to add more fuel to get a stoich fuel reading. So, either your upstreamO2 sensor is telling the ECU false info and needs to be changed and/or you have some sort of fuel supply issue. "B1 S2" is your downstream (aftercat) O2 sensor. If your running that lean you may have done damage to the cat and/or downstream sensor. Check your fuel pressure to start, clear your codes, and re-check.
-Will
PS- O2 sensors are cheap compared to other engine components. If they are NOT new, I personally, would change them just to get a good base line, but thats just me.