2006 Dodge P0299 low boost code

[Jeff Johnson]

I have a 2006 Dodge 3500 with a g56 manual. I bought it used and it was already modified. It has s big turbo, new intake, tuning, 40psi boost, etc... I don't drive the truck like a kid but, whatever, the price was right and all this was already done.

Anyway, I just got my second low boost code within the last couple of months. The first time, I had been pulling a heavy trailer for a buddy. Everything was running normal. I stopped at his house, dropped the trailer off, then the truck was gutless going home. I had a P0299 code, so I decided to deal with it in the morning. The next morning, it was still gutless. I took the boost fooler out and it ran normal again. I put it back in to prove that was the problem and it still ran normal. I just figured "huh, bad connection."

Last night the truck ran fine and this morning I had the P0299 again. I thought "No problem. I know how to fix this." I tried pulling out the boost fooler, but this time it didn't make a difference.

The computer is reporting boost values that seem to match what the mechanical gauge is showing. The most boost I can get is 5 or 6 psi. There is no black smoke because the computer simply won't send enough fuel. The throttle pedal is reporting full travel (0-100%). I have an Air Dog fuel pump and It's coming on. Everything acts normal up until the point that the computer wants to see boost, then it just never gets any more power.

Is it possible that the MAP sensor is sending values that LOOK normal to a human, but are just a tad too low for the computer to like? It seems that the failure mode would be all or nothing. This issue didn't come on gradually. It was fine one day, not the next, fine the next day, now not fine. I have no problem buying a map sensor, but I hate throwing parts at a guess.

 

[Jeff Johnson]

Here's another wrench to throw in... I stopped at the store and, when I came back out, it's working fine again.

 

[Bob Wagner]

The code needs to be cleared out of the ecm to fix the issue. Your turbo is too laggy and senting the P299 cose. Its bben an issue for over 10 years.

 

[Jeff Johnson]

I was a powerstroke owner (gross, puke) before this, so this is new to me. I think I know what's happening and why it seemed so random. It only happened when the oil is cold - and, therefore, thicker. This may be just enough extra drag to trip the code. I'm using two programs left over from my previous truck - Torque pro and Car Gauge pro. Both read the codes and both attempt to clear them. Car Gauge knows what P0299 is, but doesn't have any success in clearing it. Torque seems to clear the code from the "active" list, but doesn't clear it from memory. It also seems that, after clearing the code, the truck needs to be shut down and re-started before it takes effect.

I'm pretty sure I tried clearing the code without shutting down the truck, didn't see any success, shut the truck down to mess with the plugs (in the mean time, the code reset with the power off), then started the truck back up and saw success. It confused the heck out of me.

 

[JRMora]

Have you checked your wastegate on the turbo? Sounds like it could be sticking open. Had this issue once - couldn't make over five pounds of boost, truck could barely get out of it's own way.

 

[p-Bar]

There are a couple wires that run underneath the AC compressor. They get frayed and short out the 5 volt circuit for the ECU.

 

[CharlesHoward]

I've gotten the 298/299 Boost codes consistently now (Sept 21) despite having a "new" BD Exhaust Manifold and BD Turbo (no wastegate) and having towed my 14K lbs Fifth Wheel from AL to IA in April successfully.
My Scan tool clears it but the Check Engine light returns with this code and the Truck is sluggish for a bit until I really push it...
I know my Catalytic Converter is toast and it rattles a lot until we get moving or at idle.
Could a "choked" up CAT cause this issue?
Will I be able to tow my trailer home next month?

 

[CharlesHoward]

Further online Research suggested the MAP Boost Sensor could be bad. With 172K miles possibly....
I ordered one but may not be able to install myself as I don't have all my tools with me....

 

[AH64ID]

Does your scan tool let you monitor any sensors? That would be an easy way to see if the map sensor is bad.

06-07 5.9’s don’t like laggy turbos and will throw codes easily for them, but normally not as issue on a 03-05.

What BD turbo do you have? Any programming?

 

[CharlesHoward]

I don't think my consumer grade Scan Tool can search... would the MAP throw its own Fail code directly if its clogged but still connected/live?
BD Iron Horn (level 2) installed Nov 2019, only 4+K miles ago. No tuner stock 5.9 with Mr Bob's Hoses, BD Intake Manifold, homemade 'Cool Air Hose" to the stock Filter and Box.

 

[AH64ID]

That shouldn’t be too much turbo.

I would get your cat cleaned out or replaced. If it’s blocking exhaust flow it could effect spool.

 

[CharlesHoward]

Well my first ignorant suspicion was the Catalytic converter but the local Shop had quoted me $1500 so I planned to DITY when I got home to AL... but now I went ahead and ordered a Magnaflow "Bolt - On" Cat for almost $900 (S&H) as I do have a Sawzall (while working in IA at King of King Lutheran Church while camped on their Parking lot) ....I understand that's all a CAT Thief needs!
Hopefully a new IAT/MAP and/or Cat will return my RAM to normal performance.

 

[JKosten]

What was the outcome from this? Did you end up replacing anything or having the issue again?

 

[CharlesHoward]

CAT was replaced with a Magnaflow in IA. Traffic Jam/Stopped on I -65 in TN On the way home to AL led to another LOW Boost Code and Limping to a Campground. Got to a nearby Diesel Shop by 4 PM and they checked things out and their Super Scanner Cleared the Code.
Successfully towed my Fiver early this month to Imperial NE (1300 miles $850 in Diesel) from AL.
Visited Greeley CO sans Fiver, hit a bad steel road plate on a Friday, set a Communication Code. Cleared that, then Low Boost Code again. My Cheap Scanner claimed to clear the Boost Code 3 Times but still had Check Engine Light UNTIL the Sunday we returned to NE (Mystery that it just went away)... No problems since (albeit NOT towing).
Ordered a new MAP from Genos and local NE shop will get to me for an install later in July.
I hope that puts an end to low Boost Codes!