Advice? - codes P0135, P0141, P0155, P0161, P0443

[springer]

I have searched this, and found a couple of threads that tell me this is likely a computer issue. However, I wanted to reach out for advice to make sure, and also on purchasing a remanufactured ECM or sending mine out for repair.

Background:
The issue started day before yesterday. The Merc seems to be running fine - its my wife's DD. She thinks it runs the same, I thought it was fine when I tested it.
* Battery is new (January 2021 - Optima Red Top) At the battery, I am seeing 12.5v when static, and 14V when engine is running
* fuses 38, 42, all the 15a fuses on that row are fine & have power on both sides when the ignition is on.
* I have a cheap scanner & can clear the codes. They come back, but not right away. For example, I cleared the codes, then drove it around the neighborhood (probably 1-2 miles) & the codes did not return. Then my wife drove it on errands, made one stop, no codes, then codes came back when she started the car to leave. (only parked for minutes). Another time, the codes came back mid-trip (while driving) - that seemed odd to me as I assume the O2 heaters are part of start-up.
* Visually, I do not see any wiring issues. All wires (that I can see in a non-invasive inspection) look new and unscathed. (I have owned the car since 2008, it was a Ford Executive Program Car (original owner for less than a year) and I have done all the maintenance. No major issues.
* I replaced all 4 O2 sensors as part of routine maintenance at 100k, the Merc now has 150k. I think I bought Bosch O2 Sensors.
* Also, I dropped the spare and looked at the vacuum lines going to the filler door (capless fuel filler) and aside from being dirty, look fine. I don't see any cracks or obvious leaks.

I understand that it could be a wiring issue, but I highly doubt it. Also, I cannot imagine that (the heater circuit for) all 4 sensors would fail simultaneously, unless it is possible that 1 can fail (short internally) in such a way as to interrupt the other 3. It would also really surprise me that the computer would fail, but I did see an extremely detailed write up of how this can happen and is a weakness of the computer itself, so I am leaning towards this possibility.

So, does anyone have any advice, or is there anything I have not considered? Also, has anyone used a repair service for the ECM that they recommend? I found MODULEREPAIR on e-bay at $250 (ship yours to them for repair) and "Car Computer Exchange" recommended on YouTube, which appears to be $700 and they ship you a remanufactured unit and you ship back your old one.

I can do without the car for a few days or a week, although letting my wife drive my Ford Lightning makes me cringe a little... LOL. The brief search for the computer repair surfaces a big difference in prices, and if I purchase a remanufactured unit (they claim to be pre-programmed), is there any issue with the keys/remotes (PATS) - assuming the keys are chipped ( I thought they all were, but I don't see a chip. I have the two original keys and fobs.)

Thanks in advance, sorry this is long.
--M

 

[springer]

Nobody (yet)... ???
Thanks for looking - if you have any advice, please let me know.

I found Module Repair Pros on e-bay, also linked in a similar thread, and they seem responsive when I asked a question, so I am planning to use them.

My question is - since they are sending you back the same computer, I assume there is no need to have the keys reprogrammed, or anything like that. Should be "plug & play" - is that correct?

What I was noticing with some of the "exchange" sites is that they send you back a "reprogrammed to your VIN" computer, but with the caveat that you may need to have Ford or a mobile locksmith reprogram the PATS system (or I think you can do that with FORScan, which I don't have but probably should get), and I was trying to avoid that extra step, and the exchange sites are WAY more expensive. The delay in shipping my computer out and back is not a big deal, as long as I am not getting scammed...

 

[Rcflyer330]

Well I cant help much with diag or what the problem could be here is a suggestion before you do anything. Alldata diy is a paid service (its not that expencive) will have the wiring diagrams to check for power and grounds. Some specialized tools a multimeter, test light, and a dc amp clamp to check for amp draw to the heater circuit. It sounds like you are missing a power or ground. The only way to find out is with a wiring diagram and some test equuptment.

If you dont know how to test for power and grounds look up pine hallow auto diagnostics on youtube and watch a few of his videos. Just about every video he is checking for power or grounds.

 

[springer]

Thank you for the suggestions. I do have that equipment and know how to test power and ground!

 

[willied]

Let us know if you figure anything out. I think I'm having the same problem.

 

[springer]

All,
I wanted to follow-up with the resolution. The problem was with the computer. As noted in other threads - apparently the O2 heaters draw power through a circuit in the computer and that circuit can burn out or fail.

Buying a refurbished computer not only is an expensive option, but my research leads me to believe that the keys will need reprogramming because the PATS system will not be synced to the new ECU. So, I sent my computer to Module Repair Pros (I have no ties to them - found them on e-bay when searching for an ECU.) The Module Repair Pro folks answered my questions very quickly, so I gave them a shot. Other than the shipping from Texas to California and back taking about a week (not their fault), the process was very fast.

I reinstalled the computer and have not seen any codes reappear in at least two weeks of driving, so I am very happy with their repair. The Merc is running just as smooth as before, so all is well. (One issue I did not mention previously is that when the check engine light came on, the car would stumble and low idle briefly, then run fine. That has not reoccurred.)

FYI - the repair cost $250 + $16 shipping.

Also, my notes on removing the computer -
Be sure to disconnect the battery, and wait 10-15 minutes or turn the headlights on and open the doorscharge any remaining current.

I also used latex gloves to make sure I had no static electricity built up.

The three plugs on the ECU are easy to remove, and are different sizes, so they cannot be mixed up (although I still labeled them and taped a baggie around the open plugs to make sure they stayed dry since they would be exposed for a week or so).

to remove the ECU (at least on a V8 car) - you will need to remove the entire airbox (top and base). I also had to remove two nuts holding a clamp for the AC lines on the wheelhousing, and rotate the clamp up out of the way, in order to be able to slide the ECU out of the bracket.

The two nuts holding the clamp, as well as the two bolts holding the ECU are both 11mm (odd size).
Once you remove the two bolts on the computer bracket, you should be able to slide the ECU out (with some wrestling... LOL) To reinstall, reverse the above. I also rubbed a thin layer of dielectric grease on the harness plugs so that they would slide in easily.

​

 

[springer]

Let us know if you figure anything out. I think I'm having the same problem.

Sorry - I was trying - NEVER hit the "back" arrow - that screwed everything up and I had to log out and re-log in to get it to post.

 

[willied]

Sorry - I was trying - NEVER hit the "back" arrow - that screwed everything up and I had to log out and re-log in to get it to post.

Haha no worries. Thanks for the write up! I will probably end up doing the same.

 

[06MountaineerPA]

Wow, this is great. I been having the same codes and thought the same thing about how could all 4 O2 sensors fail at once. Did your EVAP code go away, P0443?

No reprogramming require for the PATS / keys?

 

[Bazz270]

O2 sensors and Evap equipment shares the same grounds,

Since PCM dont have any back current fuse,most probably for the PCM related circuits to be shortened and burned.

Check yours harness for bad insulation.i dont believe about self PCM destruction.something caused the PCM to be bad.

 

[06MountaineerPA]

Do you have a wiring diagram showing the same grounds and where it's located, so I may check it. Before I order a new PCM, like what he did above.

 

[Bazz270]

See workshop manual/electric wiring section

 

[springer]

Wow, this is great. I been having the same codes and thought the same thing about how could all 4 O2 sensors fail at once. Did your EVAP code go away, P0443?

No reprogramming require for the PATS / keys?

,Yes, the EVAP code did go away. Also, yes, no reporgramming for the PATS/Keys.
So far, still working flawlessly.
The grounds were NOT the issue, unless the ground is inside the computer (according to the post - its is something on the circuit board that needs repairing, so I did not open the brain to inspect).
The reason I went this route is that another post mentioned that the O2 heaters were activated by a relay (my interpretation) inside the computer, and that circuit can fail. That is why I sent mine in, and the company on e-bay fixes these computers specifically for that reason, so I am not alone.
I performed a visual inspection as well (before going the computer route) and could not find any wiring that looked chafed or damaged. I bought my Merc in 2008 (used but almost new) and am the only one who has serviced anything on the vehicle.

 

[springer]

O2 sensors and Evap equipment shares the same grounds,

Since PCM dont have any back current fuse,most probably for the PCM related circuits to be shortened and burned.

Check yours harness for bad insulation.i dont believe about self PCM destruction.something caused the PCM to be bad.

I am with you - I typically would NEVER jump to the conclusion that the computer is bad - but in this case I think that is exactly the issue. It has been around a month since I sent it out for servicing, and no codes have reoccurred. Prior to that, I could clear the codes and they reoccurred the next time the Merc was driven, although not right away - usually while driving, or the second or third time it was started. My wife drives the Merc every day (kids to school, cheerleading, volleyball, etc...) so its not sitting around.

 

[willied]

Does the lower part of the airbox just pull out? I can't seem to get it out.

 

[Bazz270]

V8 Airbox bottom part simply seated on the four body bushings.

 

[willied]

V8 Airbox bottom part simply seated on the four body bushings.

Okay, thanks!

 

[willied]

I guess I should've made an update. I got the PCM back in and the CEL has been gone since! Thanks for the help!