Hey everyone! Looking for some assistance regarding some trouble codes I pulled this morning from my son's '96 F150 I6. The check engine light was on and I used my very basic code reader ($60 Autozone).

Some precursor information: I replaced all of the 02 sensors a few months ago along with the smog pump, plugs, rotor and cap, alternator, battery and serp belt. I also used some exhaust wrap to eliminate some leaking on the secondary air tube (on top of engine), and there is squeaking coming from the water pump area (no leaks yet). And the airbag module was removed a few months ago due to a short in it.

Here are the codes:

P0133 02 Sensor Circuit Slow Response (Bank 1 Sensor 1)

P0135 02 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)

P0141 02 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)

P0155 02 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)

P0171 System too Lean (Bank 1)

P0174 System too Lean (Bank 2)

P0385 Crankshaft Position Sensor B Circuit Malfunction

P1131 Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 1

The truck has constantly thrown codes for the 02 sensors since we got it last year. Where do you think I should start, uh continue? Any detailed advice is appreciated as my son has no internet service and lives 30 miles south of me. So I will try to help him via phone.

 

If you had a more advanced code reader, you can read the voltages of the O2 sensors to see if they are in fact the problem or elsewhere.

You can also test the sensors themselves, I think they should read more then 5 Ohms, but usually the circuit malfunctions are caused by damaged wires and corrosion.

As for P0385, that may be an intermittent problem. If you clear the codes, start the engine and rev to about 2k for about 10 sec a few times, pull the codes again and see if its there again. Because of all the failed circuit codes I would assume you have a bad ground somewhere or corrosion in a harness. I would also check the harness at the PCM.

 

Yeah, unfortunately I only have that basic code reader. It's up to my son if he want's to go have it checked somewhere, so we'll see. I'll see next time I have the truck here if I can test the Ohms on the sensors themselves. They should check out though seeing they're relatively new. However like you mention, the wires could be damaged/corroded.

Corrosion make sense as the truck has had a lot of moisture over time under the dash because of the rusted out pan in the cowl vent area. I'll look into that regarding any related area circuits.

I had the plugs off the PCM a few months back and cleaned them up with electronics cleaner and sprayed them with protector too. I'll check them again though, thanks!