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CA - Cannot Pass Smog with Code 155!

wdwacht

Member
Joined
February 22, 2007
Messages
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City, State
South Redondo Beach, CA
Year, Model & Trim Level
'97 Explorer Sport Manual
20121018 - The culprit was the wiring harness as thought below. It's all fixed now and running like a Champ!

Greetings! My lil 1997 Ford Explorer Sport Manual v6 OHV with a persistent CEL code of 155. I need help! It won't go away no matter what I do.

Initially I got a code for the rear O2 sensor, so I figured they were all about the same age so I replaced them all. The initial code for the rear one went away but then this CEL 155 came in its place and it's been persistent ever since.

I also, while I was at it, put in a new serpentine belt, flushed and cleaned the radiator, and installed a new thermostat and top hose.

I replaced the one sensor for the 155 again bank 2 sensor 1 (Drivers Side pre-converter) and checked the local grounds. I'm thinking now maybe it's the wiring harness? This code did not show before I changed out the old one. (Yeah I broke the danged thing!)

Also it's over heated a few times since I've done the work and put the new sensors in it. Sometimes it will take several days for the CEL to throw the code after it is reset with the reader. I'm at a loss here Fellows! And my smog certification is overdue.

I greatly appreciate your assistance before I relent my checkbook to the repair shop. :salute:

regards,
Will

Ok, after taking my little ******* to my last resort shop here's what was discovered and hopefully has resolved the situation. I'll find out after a good drive today.

After checking the three O2 sensors, fuses, inspecting the wiring, and then the voltage, with no glaring cause. The Mechanic pulled the front of the wiring harness off that connects to the back of the engine. He notices it was kind of slack and never properly wrapped all the way to the connecter. Come to find out a ground wire had been rubbing against the firewall and was slightly bared open. This was enough to 'occasionally' ground out when I was driving and simultaneously turn me insane! The CEL would come on erratically after days of driving, no where quickly as fast as it would if it was steadily grounded. So he taped it up good, secured it better and I'm going to drive it for awhile today and then he will check it out again. If all is good then I can finally complete the smog check on the fourth attempt! I am the original owner of this vehicle and am certain that no one ever took the danged thing off to check it but now ascertain that it was never wrapped and secured properly from the factory in Louisville, KY. Hopefully is this mystery is now resolved it will benefit this group in general so as to never have to go through this extended level of work effort and continuous frustration! All in all I still love my little machine.

Cheers!
Will :)

2012/06/25 - Awww it's still tossing the P0155 code. Wiring is good and voltage checked, fuses checked, O2 Sensor replaced again, it still is occasionally over-heating. The Mechanic suggested a new PCM but that's it as he is exhausting the possibilities here. Can a PCM be partially bad?

Happy Munday!
Will
 












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