P0472 - Exhaust Gas Pressure

[hwebster]

Well I have had a few codes over the last 2 months, replaced the barometric sensor (seemed to fix the problem for a while) and then it came back and the exhaust brake wimped out. I couldn't clear the DTC - flashed the ECM a few times, shifted the settings and zilch. It pops up as soon as I start the truck.

Pulled the sensor, started up the truck and the overall flow from the port was minimal. Flashed the ECM again, cleaned the sensor, port and the tubing. My repairs guys seem to think it's an ECM issue.

Got the cost of a new ECM from Dodge and hucked a hair ball.

SO I am looking for some guidance here.
1 - I'll get a remanned ecm (Once I find the ()*&@#$() part number for the one in my truck) Any one know how to find out which ECM is in my truck easily?
2 - Can I be certain it IS the ECM? Could the Turbo be an issue? Blockage in the exhaust system? SOmething Else?

Oh the joy of it all!!!

;-)

 

[Jim W]

What year of truck do you have and how many miles on the OD?

According to a few posters on this site who are former dealer employees. THE ECMS do not fail. Several posters have purchased after-market ECM’s and found out that this was not the problem and are out the cost of the new ECM.

I would do a search for threads on your CEL codes and see what the response is. There is also on the left-hand side a heading of Ram Diagnostic trouble codes. You can google the DTC and find out what is the real problem and resolution.

We can all guess what the problem could be but until the DTC is provide it is just a WAG!

 

[hwebster]

2008, 220,000 miles...smarty P0472 is the code I found and can't clear...

 

[AH64ID]

Have you inspected the wiring?

 

[hwebster]

Wiring is a potential had a major issue where most of the wiring was ripped out by the front drive shaft...

 

[AH64ID]

Wiring is a potential had a major issue where most of the wiring was ripped out by the front drive shaft...

Sounds a lot more like this would be the issue than an ECM issue.

 

[hwebster]

The wiring was ripped out last year, the harness to the read of the truck, the harness between the Transmission and transfer case (which Dodge discontinued!), the hydraulics to the clutch etc. Quite a mess. However it has been running quite well until this little episode. I am not sure where to start... There seems to be little exhaust gas when I pull the sensor. Is there a valve or gate somewhere that could be faulty? The Turbo it self? Variable vanes pooched? Likely a cheaper fix than a stock ECM!!!!

 

[AH64ID]

There isn’t a lot of back pressure at idle.

You use compressed air and put 1-2 psi against the sensor and see if the CEL goes away.

 

[Ozymandias]

I found this.

https://www.obd-codes.com/p0472

Like said, circuit problem. Very rare the ECM.

 

[Jim W]

I would look at the pins in your wiring harness at the connection to ensure they are seated in the connector in the harness and connecting to the sensor. I would also check both ends to. A loose pin connection can cause an electrical issue also.

I would also check continuity between each pin in the wiring harness using a Multimeter. This will ensure you do not have any broken wires.

When you are sure that the pins are tight before closing up the connection put in some Dielectric grease into the joint at both ends.

 

[hwebster]

Thanks Jim.. I'll do that asap... H

 

[sag2]

If it is an exhaust pressure sensor code, pull the steel line between the manifold and coolant elbow and make sure it is clear. Also make sure it is clear at the elbow and manifold.
If all that is clear you need to verify the wiring between the ECM and sensor. It is a 5v 3 wire sensor so you need to see 5v on one wire (pink/yellow), ground on the other (brown/orange), and the third wire is the signal wire (brown/Dark Green). Be VERY careful probing the connector pins.

 

[hwebster]

THanks Ozymandias, Jim W and sag2.. Will try all of these still no joy but... at least it isn't -40!

 

[hwebster]

Update...

1st the good news... After much digging, I finally pulled the ECM and sent it down to Auto Computer Specialist, Inc. at 221 S State Rd 7 in Plantation FL . They were able to diagnose and repair the issue with the ECM.

Now the bad news... Before I can reinstall the ECM I need to either replace the main engine control harness and the Transmission Control Harness or have them repaired. Of course these have been discontinued by Dodge.

Has anyone removed these harnesses and have any advice on how to pull them? There isn't anything I can find in the service manual.

Needless to say, the prospect of an easy fix of just bolting the ECM back in has just evaporated...

 

[sag2]

So if the ECM fixed the problem why do you need to now replace the harness? Pulling a harness is just a matter of disconnecting it from all the attachments and modules etc. nothing difficult about it, just time consuming.
If it is no longer available you might try a newer year and use it to make a repair.

 

[hwebster]

Hi SAG2,

The ECM has been repaired and is in transit. The VERY detailed report indicates that there are shorts in both cables, no surprise given the recent history of my ride. They suggested replacing them or repairing them before installing the repaired ECM. If installed without repairs the warranty is void. Since replacing them with a new one from Dodge is out of the question R&R is the only option. One is 3/4 disconnected, along with a lot of other components (big hands). Hoping to finish today. The plan from there is to send the harnesses to Autocomputer and they'll repair them, that way at least I can be certain the wiring isn't going to be a continuing issue.