Engine Check - PNN?
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Mountain Pass
Joined: May 2002
Posts: 190
Likes: 3
From: Southern California
Engine Check - PNN?
I just got off the phone with the Ford Dealer and was told the reason for the E.C. light was a bad PCN (a computer module "brains" for the engine. They want $516 to relace (parts and labor). Ouch! The error codes are P0155 and P0141. ANy advice out there? Any idea on what might have caused the failure. Truck is 97 F250 HD Crew 4x4 with a 460. Recently had the TTB swapped out for a Dana 60. Also have a spuratic Vacuum sounding noise coming from the engine sometime accompanied with a whining sound.
Thanx
John
Thanx
John
Posting Guru
Joined: Aug 2000
Posts: 1,984
Likes: 2
Engine Check - PNN?
John, those codes relate to the HEGO sensors. They indicate a "heater circuit failure". I suppose the PCN might cause this, assuming the wiring to the sensors is intact.
The vacuum/whining noise is probably from the idle air control (IAC), and is unrelated to the other problem.
The vacuum/whining noise is probably from the idle air control (IAC), and is unrelated to the other problem.
Post Fiend
Joined: Nov 2002
Posts: 9,987
Likes: 7
From: Memphis, TN
Engine Check - PNN?
PCM - Powertrain Control Module, aka EEC - Electronic Engine Control, aka OBD - On-Board Diagnostics.
If the computer is spitting out codes, it DOESN'T need to be replaced and that service advisor should be shot. If they don't want to fix your truck for a fair price, just get the Ford/Helm service CD that they use off eBay for ~$10 delivered to your door and fix it yourself. Since you already know the codes, you can look up the pinpoint tests on the CD and find your fault.
If the computer is spitting out codes, it DOESN'T need to be replaced and that service advisor should be shot. If they don't want to fix your truck for a fair price, just get the Ford/Helm service CD that they use off eBay for ~$10 delivered to your door and fix it yourself. Since you already know the codes, you can look up the pinpoint tests on the CD and find your fault.
Thread Starter
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Mountain Pass
Joined: May 2002
Posts: 190
Likes: 3
From: Southern California
Engine Check - PNN?
I spoke with another Mechanic at a dealership where I have family working. He basically said the same thing. I pulled my truck out of there and am taking it to this dealership. I will post the outcome.
Thanx for the input.
John
Thanx for the input.
John
Post Fiend
Joined: Nov 2002
Posts: 9,987
Likes: 7
From: Memphis, TN
Engine Check - PNN?
I think places like JCWhitney sell a cheapo that lacks full function for ~$150. If you want a full-function scantool that can read & write Ford codes, plan on $300-700.
Just get a parts store to do it for you.
Most of them do OBD-II codes free now. 
Just get a parts store to do it for you.
Most of them do OBD-II codes free now.
Senior User
Joined: Feb 2003
Posts: 140
Likes: 1
From: Arkansas
Engine Check - PNN?
If the computer is spitting out codes, it DOESN'T need to be replaced and that service advisor should be shot This happens fairly often when one part of the internal pcm fails, it will spit out a code and still be defective.
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