Last month my engine light came on my 2000 Dodge Ram 5.9. Brought it to my local mechanic and he said it was a vapor leak from a hose to the vapor canister and a leak detection pump code P0455 so he fixed the hose and changed the pump. 4 days later the light came back on so I decided to bring it to the dealership since my mechanic had a death in the family. The dealership said it was the vapor canister and Duty Purge Pump per TSB code P0455 so they replaced all the lines and vapor canister and also reflashed the PCM and resmoked the entire system. No leaks. The next day he tested everything again it passed with no codes. Just to make sure he retested it and the test never completed this time. They contacted STAR and updated PCM and retested and test never finished. Contacted STAR again and they said it could be possible software issue. So the leak detection pump, Duty Purge Pump, hose and vapor canister all have been replaced. 3 days later (this morning) engine light on again. I am getting frustrated with this thing. Does it sound like my PCM is going bad? Any Dodge techs out there?

I think a bad gas cap can cause a evap code.

New gas cap fixed that on my '98 Ram. Smearing the rubber seal on the cap with Vaseline fixed it for a while but not long.

New gas cap was replaced with Vaseline. Pcv valve also replaced. Leak detection pump was replaced twice. All parts replaced with factory Mopar parts.

Well the dealership is telling me that it is my engine harness which has been discontinued. Anybody know where I can get one?

Sounds to me like the dealership is throwing parts at a problem they are guessing at. What is so wrong with the harness that they can't repair the wiring?

They sad they can wiggle the harness and the engine light will go on and off. I am going there tomorrow to see it. So far 2 different mechanics said that is a possibility since I have replacied everything that pertains to the evaporative system.

I think I'd trace the harness while wriggling it in short sections until I located the problem.

To me it sounds like they don't want to spend the time and do that.

Does this dealership have an know how to use a smoke machine? It really is the best/only way to identify Evap leaks. As for having a bad harness, well this is an electrical system and we always explain that to our customers. It can always be a mechanical or electrical issue. Not sure it would need an entire new harness, other than it will save labor hours to replace it all rather than isolate the issue and repair it. My suggestion is find a better place to take your truck to for repairs. Dealerships want easy profitable repairs, not necessarily the time consuming diagnostic and electrical repair stuff. BTW the wiggle test is pretty common diagnostic approach these days. You would be surprised how often it works.

Oh yeah FWIW the last one we had actually had a crack in a rubber grommet that was the issue. The evap line had a rubber connection from the one of the plastic lines that had dried out and cracked. We found it with a smoke machine. After it had been to a shop without one that just kept throwing parts at it. A lot of shop tend the throw parts at evap leaks because they don't want to invest in a smoke machine.

A smoke test was done numerous times. The first time they did that they found a leak from a line going to the vapor canister. Fixed that. Did more numerous smoke test and nothing. They ended up checking the harness. They wiggled the harness and load tested ckt k52 and f12. They did some other tests and found high resistance (open circuit) when wiggled at circuit k52.

wiggling the wires and getting a failure means you have a bad connection or a broken wire. corrosion/fretting/failed crimp, etc...shouldn't be too hard to find. I don't have an FSM handy...what do these circuits control?

Corossion and broken wires are common especially here.I dont know how many GM headlights Ive fixed because of crappy soldered connections in the front.I guess they figure it was good enough to get out of warranty so why worry about it.Last front harness I did on a Sunfire cost was almost 600 bucks.Plus mark up and labor.Rocky

Code P0443. Still battling the problem. I got a tune up 3-4 weeks before this whole fiasco. Can a tune up cause this?

Had this problem with a truck I owned, the plastic around the fuel pump was cracked. Being on top of the fuel tank you couldn't see any smoke until you dropped the tank.

This is a common problem with mopars of that era i had a 03 chrysler t/c and my son had a 02 durango that would come up with evap codes all the time . i got the van thru emissions barely by my sons friend worked at a place that did emissions and got it to pass . but from what i heard the plastic hoses and nipples crack on the fuel pump module .

P0443 is a CIRCUIT prob... not an evap system prob..... but keep trying those different gas stations!

I'm dropping off my truck to my mechanic (not dealership) on Monday. He is also stumped. The dealership sounds like they are done with me. They said it is in the wiring harness and too time consuming.