PCM Fault codes - P0135 P0155 P0443 P0645

Hi all

I am new here on this Forum but have had my GT for 15 years.

My name is Helgi and I am from Iceland but live in Dubai.

I have a Mustang GT 2006 4.6l 3v Automatic

I have done some upgrades, mainly suspension and engine.

• Cold Air Intake
• Bama X-Rev tuner
• Steeda Underdrive Pulleys
• Ford Racing Camshafts
• One Piece Aluminum Driveshaft
• Rear Diff 3.73:1
• BBK Long Tube Headers with Cat X-Pipes and Borla Axlebacks

The car is now at 100K miles and has developed some issues I have trouble with … I am starting to lean towards bad PCM but would love to get opinions from fellow members

1. Fault light does not come on even there are codes existing. Does not light up when ignition is switched on. Might be bad bulb.
2. Two codes always come on within few seconds of starting. P0135 and P0155 (Have replaced both sensors twice)
3. Two other codes always come together but are intermittent P0443 and P0645. I notice when they drop out as the one code is the AC clutch. I find the AC smell immediately when clutch is disengaged (have replaced the evap unit and AC Clutch Relay and AC Compressor with Clutch)
4. One code comes occasionally.. P0011 usually only after a long drive 150 miles plus (have replaced the VCT Solanoid)

The car also shows some symptoms when driven. There can be difference in performance… often I notice the engine bog down a bit when the ac cuts out (codes P0443 and P0645 coming on) and then get fresher when ac start working.

I haven’t been able to figure out any fuse or common electrical connection which could cause this.. some of the items belong to Fuse 47 but not all and some are intermittent while others aren’t.

Right now am guessing it must be PCM .. all input is appreciated

Hi Bullit

Thanks for your reply and input on my thing..

As has been UAE res then you must realise how urgent it is to have AC working in beginning May .. lol

I knew what all the codes were and thats why I have twice changed both oxy sensors and also changed the evap unit

The ac code says AC Clutch circuit.. and I can see how the clutch cuts out and then drops in.. and when I bypass the relay then all works normally.. so changed the relay and changed compressor with new clutch installed.. still all same.. and what drives the ac clutch relay is the ground going to the relay and is coming from the PCM.. so when the acl clutch stops working is because it wont get ground from the PCM...

and why do the ac clutch code and the evap code always come and go together... they are intermittend and act like twins.. so been trying to figure out what do they have in common.. and only thing I found yet is the PCM...

I have also found info from one of the PCM repair companies in USA that if you send them a unit which has the P0135 and P0155 fault on it then is more expensive than other repairs.. so looks like that is a common fault with the 05-09 PCM ?

Bullitt95 said:

It isn't a common problem and it makes me wonder whether the mechanics who installed the headers might have messed up some wiring underneath the car. All the codes point towards electrical issues.

Click to expand...

These codes had already been around for over a year and 15,000 kilomters before the exaust was changed. When was changed then did put in extenders for the sensors and both sensors brand new straigt from Ford dealership.. no change at all. All wiring and connectors were double checked and all looked perfect.