Hey all, I've got a '07 1500 5.7L 2WD with 165k on it. After a wash at the local coin wash, the truck gave several long cranks and failed starts in the wash bay and the CEL comes on. It finally starts and I'm able to pull it out of the wash bay and park. The engine dies. After several more very long cranks and failed starts, I get it running and leave it running for a while, revving it periodically and everything seems fine. I shut it down and start it up again, a slight cough but it starts up and idles fine. I decide to drive it home (bad idea) and it dies on me about 8 times on my 1 mile drive home. I pulled over several times to let it run for a while, It idles fine but as soon as I pull onto the road and apply light throttle it dies. I finally get it home and check the codes, its throwing a P1128, P1129 and P0122. Now 3 days later after the truck has sat and dried out, it drives fine with no issues and no codes.

These are:
P1128 - CLOSED LOOP FUELING NOT ACHIEVED - BANK 1
P1129-CLOSED LOOP FUELING NOT ACHIEVED - BANK 2
P0122 Throttle Position Sensor/Switch A Circuit Low Input

Now, let me tell you my history with this truck. When I bought it a little over a year ago I made the terrible mistake of pressure washing the engine bay. Immediately afterward it was throwing a bunch of codes and also dying while driving. It was throwing various codes at different times and acting very erratic. One of the codes was a TPS code. The problem came and went for several weeks and I finally took it to the dealer, they had trouble diagnosing the problem, first replacing the throttle body, then saying the PCM was fried from the engine wash. After that was replaced I walked away with a $2800 bill, but the truck seemed to have been fixed. I swore to never wash the engine bay again, and put about 3000 miles on it over the past year without a single issue.

Now I don't trust this truck as far as I can throw it. My hunch is this has to be a short circuit, being that it is so closely associated with being washed. I did hit the wheel wells briefly on this recent wash, and I also have a hunch its a short on one of the sensors or wires near the oil filter where water would have been able to hit. I have gotten under the truck and looked for any kind of worn wire or obvious issue with a sensor and I can't see anything.

There is nothing I hate more than an un-diagnosed intermittent problem. If I can't replicate this problem and fix it I'm going to sell the truck. Any help you guys could provide would be greatly appreciated.

 

Something got wet, and is now causing issues. Since you have a TPS code, check the connectors for that, make sure they are clean, and dry.

 

The TPS was dry and untouched. I never sprayed the engine, just the wheel wells so it would have to be one of the lower sensors or wires.

 

Did you look at the 02 sensors ?, maybe they got wet or frayed wire to plug , possible could have sprayed the front ones on the exhaust thru a wheel well

 

Isn't the throttle pedal position sensor under the battery?? IS the truck throttle by wire??

 

Be aware that the TIPM is pretty exposed from under the truck. You could have soaked it trying to spray out the front left wheel well. I'd pull it and check the large connectors that plug into the bottom side of the tipm - could be it got wet in there.

 

Personally, I don't pressure wash engines. A regular hosing is okay, with plastic bags covering alternator, fusebox etc. Right after washing, I blow it with a leaf blow.

 

I learned my lesson there. Whats annoying is this was just an exterior wash that caused the recent problem.

 

Ya it's quite annoying how exposed everything is on these trucks... my dad had an issue with one of his sensors caused of a puddle.