Check Engine Light Problems

I have a 2006 Jeep Liberty 2.8 Diesel. It has about 57000 miles on it and when I took it to be inspected, a Code PO 299 came up. The dealer has done quite a bit of work to it and cannot find a way to get this light to stay off. When something is done, it goes off until it is driven, then it comes on again. So far the jeep runs great, but it’s hard to pass inspection unless the light goes out. Any suggestions?

Without knowing what was involved in the “quite a bit of work” done to it, it’s hard to tell you what new things to try.

These cars are notorious for failing EGR valves. If it fails open or partially open, it will drop boost pressure and cause that code. If the dealer hasn’t replaced the EGR valve yet, then that should certainly be tested.

Everything having to do with the EGR valves has been replaced. Tomorrow I will have the list of what all was replaced. So I kind of jumped the gun. I will post more tomorrow.

Is that code for a turbocharger problem?

I’m not much of Jeep guy at all but with only 57k miles on the vehicle I have to think the cause of this problem is not as bad as may be thought and it’s possible that the dealer may be involved with some guesswork while trying to sort it out.

The code shows to be an underboost condition and other than an EGR issue I wonder if there could be a problem with the turbocharger impeller dragging a bit, the wastegate not working correctly, or the existence of an intake tract leak.
A dragging impeller can be caused by oil coking which means aged burnt oil due to not being changed often enough, overheating, etc.

Just some food for thought.

Oh JEEZU…I HOPE ITS NOT THE IMPELLER Scoring the sides of the Turbo Housing. Its WAY WAY TOO EARLY for that sort of nonsense. THEN AGAIN…I put nothing past some of these idiots out there who will UNDOUBTEDLY use Dinosaur based Motor oil in their TURBO Diesel vehicle… Which in MY HUMBLE Opinion should be FULL SYNTHETIC Engine oil…just based on Turbo Life ALONE. Conventional Oils cant stand the Heat in that Turbo…ESPECIALLY right after the engine is turned off… Turbo Timer Anyone?

ANYWHO…Its easy enough to check for impeller slop in the Turbo… and I would Like to doubt that as an issue tho its most certainly possible for sure. I would be looking for Leaks in the system first… or find out why boost is being lost…there are PLENTY of avenues for boost to leak out THAT IS FOR SURE… Just go down the list and see what you find as far as the Turbo Plumbing the Valves in the plumbing that need to hold boost pressure etc…

You can do a QUICK Turbo Impeller test by removing the intake hose off of the Turbo itself…the end play should be minimal and the Shaft should turn freely. I bet the Turbo is OK…THAT IS…IF THE VEHICLE HAS HAD THE PROPER OIL USED IN THE ENGINE!!! THIS IS HUGE…

Check the turbo shaft real quick for peace of mind…and then look into Boost leaks where ever they could occur which is quite a few places actually

MANY THINGS can contribute to lower than expected Boost pressures…and they all need to be checked within reason. The turbo is controlled by a boost pressure control solenoid that operates how much vacuum is applied to the turbo to control the boost. After that it is up to the Plumbing in the system to be able to HOLD pressure when its time to hold pressure…and Bleed it off when its time to bleed it off…this Duality is why so many things have to be checked… Bec the systems HOLDS Boost…and BLEEDS Boost whenever it deems proper…SO a few areas to check for sure.

I just called my Buddy… HE HAD THE SAME ISSUE AND I JUST ASKED HIM BOUT IT…HE TOLD ME THAT 99% of the TIME… that code comes from that hose you see on the driver side…It SPLITS…Sometimes along the bottom side and you cannot see it. That hose is $125. This was AFTER THE STEALERSHIP charged him over 1200 to replace the EGR, The Boost pressure sensor…and quite a few other things. NONE OF THESE THINGS WOULD NEED REPLACEMENT IF THE DEALER LOCATED A PROBLEM IN THE TURBO PLUMBING…I MEAN…if you have a hole in the hose…and you cant build boost…you dont need to look too many other places as to why you cant build boost. Yknow?


Well this is what has been done to date:
-Found Turbo Vac Solenoid not holding vac. Also found vac runner solenoid not switching when commanded by PCM and supplying vac to turbo vac solenoid. Solenoid and Modulator were replaced.

  • Removed turbo boost tower, it was clogging up - cleaned system, light went out for a time then came back on.
  • Removed all hosed to turbo and inter cooler, found crack in inter cooler hose. Replaced hose and code cleared. after road test it came back on.
  • Replaced turbo vac solenoid, boost sensor, EGR replaced. Code still coming on.
  • Soot removed from throttle body and replaced fuel filter.
  • Star was contacted and they suggested that injectors be removed and sent out for testing. This was not done. (how much would this cost?)
Soot removed from throttle body...

On a diesel? Well, there’s a new one on me. Part of the EGR system I guess.