1996 Ford F-150 Check engine light

Tiny
KEN GRUBBS
  • MEMBER
  • 1996 FORD F-150
Computer problem
1996 Ford F150 6 cyl Two Wheel Drive Manual

This vehicle only has 52,000 miles and has not been driven very much the past 5 years. The recent work has been tune-up items, (spark plugs, air and fuel filters, cap and rotor, and clean throttle body). The engine light comes on and when I scan the codes PO 135, PO141, and PO155 all show up at the same time. If I clear them and start to drive, it takes approximately 3 miles to store the faults again. The vehicle runs so quiet and smooth that you barely know it's running. I took a gamble and replaced the 2 front O2 sensors, and it still faults the same 3 codes. Keep in mind that this is the smoothest running vehicle, if it wasn't for the check engine light being on, I wouldn't even be worried. Thanks, Ken
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Friday, August 22nd, 2008 AT 7:24 PM

5 Replies

Tiny
BMRFIXIT
  • EXPERT
Its the o2 heater circuit
u need to check the fuses as a 1st step
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Saturday, August 23rd, 2008 AT 6:15 AM
Tiny
BRINTON
  • MEMBER
I have this same problem in my 1996 F-150 5.0 V8. I have checked the fuses as BMRFIXIT recommends, and they are fine. I was hoping that Mr. Grubbs could detail how he resolved the problem, or have others suggest solutions.

Thanks

Brinton
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Saturday, November 8th, 2008 AT 10:21 PM
Tiny
BMRFIXIT
  • EXPERT
Do u have the same three codes?
Was the sensors replaced?
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Saturday, November 8th, 2008 AT 10:25 PM
Tiny
BRINTON
  • MEMBER
Dear BMRFIXIT,

Thank you for responding. I do have the same three codes. I have replaced all three o2 sensors and still have the same codes. I have.25 volts at the heater circuit of the pigtail connection to the o2 sensor. I am not sure if that reading is enough volts for the heater circuit. The fuse for the heater circuit is fine.

It is possible that I have a ground problem or an open circuit somewhere. When I turn on the factory radio, I do get a second or so of feedback just as it turns on. Perhaps this is causing or is a clue to the codes showing as a heater circuit problem?

The previous owner had an aftermarket alarm installed and an aftermarket hitch with lights for the trailer brakes. Perhaps these are also clues.

Please help!
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Monday, November 10th, 2008 AT 7:31 AM
Tiny
BMRFIXIT
  • EXPERT
Disconnect O2 sensor and turn key ON or start check for battery power at the plug
you should have battery power at one of the wires and a ground on the other if not suspect bad wire check the ORG wire
check if the fuse has battery power
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Monday, November 10th, 2008 AT 12:52 PM

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