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My 2006 Wk Jeep with the Mercedes OM642 engine is showing…

Customer Question
Hi, Yes my 2006...

Hi, Yes my 2006 Wk Jeep with the Mercedes OM642 engine is showing DTC P0401, with an intermittent P0299. There has also been P0471, but I suspect they're seperate problems.

Mechanic's Assistant: How many miles are on the car? Is it an automatic or a manual transmission?

I have a flash scan tool which I use to reset the DTC's. Only the combination P0401 and P0471 &/or P0299 have trigerred limp mode and MIL light.

Mechanic's Assistant: What is the model of your '06 Jeep?

Grand Cherokee, in Austrlaia they sold the CRD verison from '06, unlike North America form '07. *from

Mechanic's Assistant: Are you fixing your Grand Cherokee yourself? What have you tried so far?

Yes, I'm fixing it myself. I have not tried anything yet, as the problem only presented last week. We have done two 5 hours highway trips over the weekend, and the P0471 has not come back, as I know the DPF did several regens.

Mechanic's Assistant: Anything else you want the mechanic to know before I connect you?

The engine is running the Green Diesel Engineering (GDE) Eco tune, and has had the EGR disabled as part of the tune.

Submitted: 7 months ago.Category: Jeep
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Customer reply replied 7 months ago
The Jeep has done 260,000km, and I have also been running the ProVent200 system, which diverts the crankcase gasses to the atmosphere instead of back to the intake. It's been running this since I bought the car at 216,000km. When I purchased the car, I also installed the new version of the oil cooler seals (purple viton - as they were leaking), and and a new turbocharger (as it was also leaking from the rear seal). I have also been using a K&N wet filter since 250,000. The car never misses a oil/filter change and I run it on Nulon Full synthetic 10W-40 every 8,000km.
Answered in 19 minutes by:
10/1/2017
Jeep Mechanic: Chris, Shop Foreman replied 7 months ago
Chris
Chris, Shop Foreman
Category: Jeep
Satisfied Customers: 14,667
Experience: Jeep Certified Master Tech
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Hello, my name is ***** ***** I will assist you today. P0401 sets when the PCM (engine computer) detects an issue with the EGR pergormance (too much flow or too little flow). The P0299 sets when there is a turbocharger under boost condition. Does the engine seem to lack any power when under boost?

Chris

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Customer reply replied 7 months ago
Hi Chris, no the doesn't lack any power under boost. The GDE tune really opened up the engine. When the P0299 triggered on the long drive, I also got the red lightning bolt flashing on the dash (flashing - not solid 'on'). Then it limited the boost, but still made OK power. I pulled over and reset the DTC, and everything ran fine. I saw in another justanswer.com post that on occasion the P0401 can also show P0299. I also cleaned the mass air flow sensor last week after the initial limp mode (using the proper type of mass air flow sensor cleaner). I also pulled apart the induction system from the front of the turbo right through to the intake, and inspected all the hoses, seals, and O-rings. Nothing seemed unusual, all parts were in good shape, and none of the seals were out of place or brittle.
Customer reply replied 7 months ago
Sorry, also worth saying that since I did the oil cooler seals and new turbo, (in conjunciton with the GDE tune to disable the swirl motor and EGR), I physically capped the pipe that diverts the exhaust gas from the exhaust manifold to the swirl port. You would be familiar with the part; it's a small flanged pipe, that is pictured in the attached file. The pipe part has been removed, and the flanges welded shut. It has never had any problems with this modification (running for 32,000km).
Jeep Mechanic: Chris, Shop Foreman replied 7 months ago

Okay good. Well I have seen where the EGR valve does not close completely or stick partially open. This causes excessive soot to build up on the boost sensor which in turn makes the PCM think that there is a lack of boost and then the code(s) set, So What I recommend doing is to replace or try to clean the EGR valve. The remove, clean and reinstall the boost sensor. Clear the DTC again. That usually takes care of it.

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Customer reply replied 7 months ago
Sounds like a good plan (and I was thinking of doing that anyway, so good to confirm). Where is the boost sensor located on my engine?
Jeep Mechanic: Chris, Shop Foreman replied 7 months ago

Hang on, let me see if I can find a picture for you.

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Customer reply replied 7 months ago
Just logging off now; i'll be back online in about an hour.
Jeep Mechanic: Chris, Shop Foreman replied 7 months ago

Click on the link below to see the boost sensor.

Chris

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Jeep Mechanic: Chris, Shop Foreman replied 7 months ago

Ok, I will look for your reply later

Chris

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Customer reply replied 7 months ago
Hi Chris,
I just had a thought. Since I have capped the EGR pipe, and this P0401 problem hasn't happened before (I regularly scan the car to see if there are any DTC's), is it more likely that the EGR valve is failing as apposed to it being caked up in carbon. As the EGR pipe is capped there shouldn't be any additional carbon build up that wasn't there when I worked on it back when I bought it (about 3 years ago). It seems more likely that the part is beginning to fail mechanically, than being blocked up with carbon. Would you agree? I will still take it out and inspect, but just though I'd ask you anyway.
Also, thanks for the pdf with the boost sensor.
James.
Jeep Mechanic: Chris, Shop Foreman replied 7 months ago
James that is a good point. Another thing that I was thinking, is because the EGR Valve pipe is capoed off, there really should be no flow. That would cause the P0401 to set.
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Jeep Mechanic: Chris, Shop Foreman replied 7 months ago
Because that code will set if EGR flow was too low or too high. In your case, too low.
Chris
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Customer reply replied 7 months ago
this is the trouble with DTC's; they tend to describe the symptoms instead of describing what the PCM is detecting (and determining to be out of spec). It should probably say 'voltage off spec - EGR valve'.
As the engine doesn't have a mass flow meter on the EGR system, it assumes that if the voltage it sends to a electro-mechanical valve is out of a predetermined range, then it is reasonable to assume that the system that valve is part of is not functioning appropriately.
Since, this problem has only just been detected by the PCM, I tend to think that it has nothing to do with it being capped (otherwise it's taken nearly 40,000km, and thousands of ignition cycles to detect the problem).
It's more likely that the voltage is off spec due to mechanical failure in the EGR valve mechanism.
I'm a mechanical engineer by trade, and have worked extensively with SCADA (Supervisory Control And Data Acquisition) systems in coal/gas fired boiler houses and oil/gas refineries. So am familiar with program logic and fault finding.
I really appreciate the input of someone, like yourself, who has experience with these vehicles. It certainly save time learning and failing yourself.
I'll disassemble the EGR valve and boost sensor in the next few days, and see how we go.James.
Jeep Mechanic: Chris, Shop Foreman replied 7 months ago
Sounds good James! I work with all sorts of customers. Some know nothing about how these systems work, and some of my customers know just enough to get them in trouble. It is nice when I work with a customer like yourself who understands what I am talking about.
Let me know it goes regarding the EGR and boost sensor.
I will look for your reply tomorrow.
Have a good evening!Chris
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Customer reply replied 7 months ago
Hi Chris,
I got a chance yesterday to remove and inspect the boost sensor - see attached photos.
It did not appear to be in poor condition, and had no clogging or build up on the sensor probe.
I also poked a bamboo skewer through the fitting into the intake body to see if there was a blockage inside. It came out clean, and showed no evidence of clogging.
I tend to think that I is probably reporting the truth about the P0299 code; it really is not reaching the boost set point some times.
I will also take some time to remove and inspect the EGR valve. Do you have a wiring diagram on the EGR valve? I'd like to apply voltage across the terminals to get it to actuate (once I remove it), and verify it's operation.
I was also wondering if a clogged DPF could prevent the turbo spooling enough to trigger the P0299? If the DPF is blocked and restricting exhaust flow, it would be feasible that the turbo is not producing enough boost. I know the DPF has a differential pressure sensor, but this is only used to trigger regen. Is there some way to tell when the PCM is doing a regen?
I have been considering upgrading my GDE tune to include the DPF delete.
Regards,
James.
PS; I'm really sorry to hear about the Las Vegas shooting.
Jeep Mechanic: Chris, Shop Foreman replied 7 months ago
that sensor appears clean. Let me see if I can find a wiring diagram for the EGR Valve and get bavk to you. I will also try to pull up the diagnostic procedure for the P0299. As far as a partially plugged DPF, in theory yes it could reduce boost, but to be honest with you, I have not seen that on this vehicle (yet). I will send the info to you asap.
The Las Vegas tragedy is horrible. I just don't understand why someone would randomly kill people. Evil I guess. Been praying for those folks today.
Chris
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Jeep Mechanic: Chris, Shop Foreman replied 7 months ago

STAR ONLINE PUBLICATION

Case NumberK32740265

Vehicle IssueMIL P0299-boost pressure sensor positive deviation and or lack of power.

Year2007

ModelWK

CategoryEXL

System or ComponentHesitation / Sag / Stumble,Lack of Power / Sluggish,Loses Power;DTC / Error Message;Light Throttle,Moderate Throttle,Hard Throttle - Aggressive,Wide Open Throttle / WOT;Yes - Continuously

RecommendationAlways check TechCONNECT for any related TSBs and to diagnose any active or stored DTCs. This code generally indicates a lack of boost pressure. This can be caused by a variety of issues. Make sure the customer�s complaint can be duplicated. With the ignition key in the run position engine off, check the Ambient, Inlet, and Boost sensors for all reading the same. If any one of these sensors is incorrectly reading Barometric pressure replace that sensor and re-test. If all the sensors read the same check the air inlet hoses for any splits or leaking.

Modification Date01/04/08 9:22 AM

<table width="100%" class="portalTable" border="1" cellspacing="1" cellpadding="3" '="">

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Jeep Mechanic: Chris, Shop Foreman replied 7 months ago

Here is the diag procedure for the P0299

Chris

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Customer reply replied 7 months ago
Thanks Chris,
I was wondering if the one of the ambient, inlet, or boost sensors may be failing. Where is the ambient? I know there is one just after the air filter; which is this? Obviously I know where the boost sensor is now. I was thinking about putting a multi-meter across them. But this won't measure the dynamic response.
I'll use the pin diagram when I remove the EGR valve.Cheers,
James.
Jeep Mechanic: Chris, Shop Foreman replied 7 months ago
The ambient temp sensor is behind the grille, in front of the radiator James.
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Customer reply replied 7 months ago
Hi Chris,
I keep getting notifications to rate your service.
As I mentioned, I will have time over the next few days to do the investigation on the car.
It is only at this point that I can validate your advice against the problem with the car.Interestingly in the last two trips, the car has thrown three codes every time; P0401, P0299 and P2A00.
I think I have narrowed down the P0401 and P0299 DTC's to be the same problem; there is a physical leak on either the EGR valve or block off plate behind it. These two DTC's tend to coincide with EGR activity.The P2A00 code is confusing though. I'm going to check the loom for chafing and shorts/grounding when I inspect for boost leaks. I'm not sure what else would cause the P2A00 DTC to appear.
What are your thoughts? Do you think this DTC is related the others?James.
Jeep Mechanic: Chris, Shop Foreman replied 7 months ago

James that request to rate me is an automated thing and you just rate me when you want to. I don't think the P2A00 is related but let me research this and see if I can find the diagnostic procedure for you James.

Chris

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Jeep Mechanic: Chris, Shop Foreman replied 7 months ago

James, it is possible that the PA200 may be related to the EGR issue. Click on the link below to see the diagnostic procedure. Take a look at it.

Chris

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Customer reply replied 7 months ago
Hi Chris,
Thanks for sending this through! the first part of the diagnostic is to look for intake leaks!
I will focus on finding this intake leak, and then reassess the DTC P2A00.Cheers,
James.
Jeep Mechanic: Chris, Shop Foreman replied 7 months ago

Sounds good James! Keep me posted.

Cheers

Chris

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Jeep Mechanic: Chris, Shop Foreman replied 7 months ago

Hello James, just checking in to see how it is going with the Jeep.

Chris

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