P22A1 code, CEL light, lost power on upgrade

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Gsand31415

Guest
I bought my 6 cyl 2011 used with 114k miles with a CEL light lit and a NOx sensor code and naively assumed it would be a cheap fix (I previously drove Fords and for the most part did my own minor repairs and maintenance). After belated research, I had it professionally replaced and drove the next 6,000 miles without a problem.
Recently the CEL lit again with a P22A1 code and today while driving up a mountain pass suffered a dramatic loss of power. Wife was driving and I didn't have a full view of the dash but from my angle didn't see any additional lights or messages. Crawled off the freeway and hooked up the ScanGuageII and couldn't remember how to view codes, but did get a prompt to clear them, and not really thinking things through under pressure I hit "clear". The CEL light went out and it ran normally for the couple hundred miles to get us home.
My questions:
1. Were we in "Limp Home Mode? Is there a dash indicator or is that a diagnosis by symptom?
2. If it was in LHM, would a restart have been sufficient, or was the clearing of the code necessary?
3. Should I replace both NOx sensors with the latest generation (gen5, if I remember the posts)? I seem to remember that both need to be on the same generation.
4. I'm sure I can do the mechanical part of the replacement myself. Is there also programming needed that can only be done at the dealer/shop?
5. If it is a DIY job, where is a good place to buy the new sensors?
I feel like a dope for clearing without viewing the code(s).

p.s. Since I can't create new tags, where do I find the list of existing tags
 

autostaretx

Erratic Member
"Dramatic loss of power" could simply be the turbo system dropping off-line.

With the ScanGauge you can look at MAP (manifold absolute pressure) while you're driving to see if it's properly boosting to 30 psi (more or less).
(that's a 15 pound boost, so if you're already at altitude (mtn pass), it may be a few pounds lower (say: 26 or 27).

Many things can cause a turbo drop-out, and a "turn off engine, count to 5, turn on engine" can clear the symptom.
If it's a small leak (such as a *slightly* split hose, or *slightly* loose clamp) you can drive for months without noticing it, *until* you put a heavy load on the engine ... when the ECU notices the leak, it stops even trying to use the turbo until you turn off the engine.

One of the features of the scangauge is that it's small enough to leave*permanently connected* so that you can monitor engine systems along the way.

--dick (i don't have an NCV3 code book, so i can't translate P22A1 to useful text)
Added: a little googling strongly hints that it's the "downstream NOx sensor"
This thread, for example: https://www.dieselplace.com/forum/6...des-p22a0-p22a1-service-emissions-system.html
hints that the Check Engine light will return. Actual readout of the NOx sensors would be informative. (an Autel scanner may be able to do that ... i don't have an NCV3, so i can't speak from experience)
 
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I bought my 6 cyl 2011 used with 114k miles with a CEL light lit and a NOx sensor code and naively assumed it would be a cheap fix (I previously drove Fords and for the most part did my own minor repairs and maintenance). After belated research, I had it professionally replaced and drove the next 6,000 miles without a problem.
Define the second "it" in that statement- what was it that you had professionally replaced, and why?


3. Should I replace both NOx sensors with the latest generation (gen5, if I remember the posts)?
You should not replace anything until the Cause of your Concern has been accurately diagnosed. To do anything else would be what we commonly refer to within the vehicle repair profession as "guessing", and guessing is by far the most expensive and time consuming method to repair a vehicle.
 
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Gsand31415

Guest
The well-respected shop did extensive troubleshooting with their Star system, and after swapping the two sensors and finding the error code move to the other sensor, they replaced the failed NOx sensor. It took three days and there was 150 more miles on the odometer, so I'm pretty sure they put some time and effort into their diagnosis and road testing.

In reading this forum I have come under the impression that the earlier generations of sensors are good for sh*t. My local Mercedes shop (the previous service was 3000 miles away, not here) seems to have a reputation for spotty but expensive service, and if I'm making the choice between spending $500 on their diagnostics vs. the same on more reliable sensors, I'll take the chance on my own guess. I've only used them for a recalled airbag issue, but they let me down a little on that interaction. Not a big deal, but if I was asked to give a review, it would have been a little below expectations.

I spent my career working with equipment that would give cryptic error codes when thing went wrong, and developed a talent for cost-effective troubleshooting. I know that my code(s) may actually have been caused by problems in the DEF system or elsewhere, and that's why I went with a pro the first time around.

On one of my Fords, The TFI ignition modules had a reputation as bad as the earlier Mercedes NOx sensors, and I replaced a couple of them. I also had problems with the generally reliable MAF sensors which I traced to a bad connector without replacing the sensor. I'm certainly not a pro in this field, but I do like to understand a problem before I act, so that's why I am asking these questions. I can't help noticing that you didn't answer a single one of my questions.

I suspect that others on this forum could cite many examples of being charged for the replacement of perfectly good parts at Mercedes dealers. I've read a few of these accounts. I think you have to grant me that replacement of the NOx sensors would at least be a somewhat educated guess.
 
The well-respected shop did extensive troubleshooting with their Star system, and after swapping the two sensors and finding the error code move to the other sensor, they replaced the failed NOx sensor. It took three days and there was 150 more miles on the odometer, so I'm pretty sure they put some time and effort into their diagnosis and road testing.
Time and effort mean nothing without skill. I'm glad it worked out okay for you. :thumbup:

I spent my career working with equipment that would give cryptic error codes when thing went wrong, and developed a talent for cost-effective troubleshooting. I know that my code(s) may actually have been caused by problems in the DEF system or elsewhere, and that's why I went with a pro the first time around.
Good. :thumbup:

On one of my Fords, The TFI ignition modules had a reputation as bad...
I never really concerned myself with the reputation of Ford Thick Film Ignition modules, but I have diagnosed and replaced many of them- it was a common failure point.

I also had problems with the generally reliable MAF sensors which I traced to a bad connector without replacing the sensor. I'm certainly not a pro in this field, but I do like to understand a problem before I act, so that's why I am asking these questions.
Good. :thumbup:

I can't help noticing that you didn't answer a single one of my questions.
Sure I did- I answered question #3. :thumbup:

I suspect that others on this forum could cite many examples of being charged for the replacement of perfectly good parts at Mercedes dealers. I've read a few of these accounts.
I'd be interested to see those examples, if you're able to show me.

My local Mercedes shop (the previous service was 3000 miles away, not here) seems to have a reputation for spotty but expensive service, and if I'm making the choice between spending $500 on their diagnostics vs. the same on more reliable sensors, I'll take the chance on my own guess. I've only used them for a recalled airbag issue, but they let me down a little on that interaction. Not a big deal, but if I was asked to give a review, it would have been a little below expectations.

I think you have to grant me that replacement of the NOx sensors would at least be a somewhat educated guess.
Guessing is guessing...
 
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Mike DZ

2016 View 24V (2015 3500)
"1. Were we in "Limp Home Mode? Is there a dash indicator or is that a diagnosis by symptom?"

The term "LHM" is being used by our various forum members to describe a number of different protective behaviors that programming in the ECU commands. It may be engine or transmission related.

"2. If it was in LHM, would a restart have been sufficient, or was the clearing of the code necessary?"

Some LHM will be cleared by recycling the power, as autostaretx indicates. Other "limps" require specific corrective action to clear.

As autostaretx implies, loss of boost system integrity fits the situation and symptoms you note (uphill, high demand). Inspection of boost hoses and seals would be the next step in diagnosis in that area. A small split in our boost hoses can be very hard to find, look for oil spray in the area (a small amount of oil in the boost hoses is normal) and feel the hose for irregularities.

I don't know enough about the NOx sensor system to make a suggestion about replacement. I am not sure how a NOx sensor failure would cause the symptoms you describe.
 

irvingj

2015 RT SS Agile (3.0L)
As far as question #3, yes, version 5 seems to be the "current" version of the NOx sensors.

If it can be determined which version you have... and if they're NOT v.5, It might be a reasonable idea to upgrade them, regardless of "throwing parts at the problem" inefficiencies. Hey- they did that with mine; earlier versions apparently just didn't seem to hold up very well. Not sure if they need to be the same generation, but if they're old enough, as I understand it, there can be a compatibility issue.

If you can get at yours, here's a pic of the numbers on mine, a 2015, which came with version 2 sensors (the "Q02" on the part number; the new one has "Q05" on it).

Pics were sent to me by the tech that replaced them, so I don't know if they have to be removed to see the numbers or not. No prevarication on his part -- he just replaced both of them.

Hope this helps!
 

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Gsand31415

Guest
Inspection of the turbo output did not reveal any obvious leaks. The rubber hose going down to the cooler is coated with a thin film of oil and the one going back up is dry. I don't understand the connectors on these hoses -- they all seem to be held in place by a spring-wire mechanism I haven't seen before, and they all have some play -- not a solid-feeling connection but I have a feeling that might be normal since they all jiggle the same amount.

Rather than MAP, I set the ScanGauge to Boost. It ramps up to about 10-12 psi on a normal acceleration, 20-22 PSI when going up a steep hill at about 40 mph. I won't have time to take it to a mountain pass for a couple of days where I can try it out at highway speeds and full load. I could take it up Mt. Baker but you can just go so fast between the switchbacks.

It's still driving fine with no CEL, but with a P229F code in memory.
 

Mike DZ

2016 View 24V (2015 3500)
Inspection of the turbo output did not reveal any obvious leaks. The rubber hose going down to the cooler is coated with a thin film of oil and the one going back up is dry. I don't understand the connectors on these hoses -- they all seem to be held in place by a spring-wire mechanism I haven't seen before, and they all have some play -- not a solid-feeling connection but I have a feeling that might be normal since they all jiggle the same amount.

Rather than MAP, I set the ScanGauge to Boost. It ramps up to about 10-12 psi on a normal acceleration, 20-22 PSI when going up a steep hill at about 40 mph. I won't have time to take it to a mountain pass for a couple of days where I can try it out at highway speeds and full load. I could take it up Mt. Baker but you can just go so fast between the switchbacks.

It's still driving fine with no CEL, but with a P229F code in memory.
It has been noted on the forums that some of the pressure hoses are porous which may explain the thin film of oil. There are O rings inside the joint that seal the pressure hoses. I normally run boost on my scan gauge and my max boost is 22.x. So, if you are holding 20ish psi of boost for an extended period you don't have a problem with boost system integrity.

If you do end up replacing one of your NOx sensors, I believe it has to be "taught in" at a MB dealer or independent with an appropriate diagnostic tool (Xentry or similar).
 
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Gsand31415

Guest
I hate to ask because my lovely wife was driving, but is it possible to trigger a boost shutdown by your driving habits? At the time it shut off, we were on a long upgrade in heavy traffic and she was trying to maintain 70+ mph. I suspect the pedal was mashed to the floor much of the time alternating with very brief instances of no throttle pressure at all.
 

autostaretx

Erratic Member
I hate to ask because my lovely wife was driving, but is it possible to trigger a boost shutdown by your driving habits? At the time it shut off, we were on a long upgrade in heavy traffic and she was trying to maintain 70+ mph. I suspect the pedal was mashed to the floor much of the time alternating with very brief instances of no throttle pressure at all.
Even the tiniest of leaks can eventually be noticed by the ECM, at which point it will cease using the turbo.
Stressing the system to "edge conditions" can help expose them.

So "driving technique" can be a factor, but that actual *cause* is still in there.

My resonator finally cracked enough 250 miles into a 1500 mile trip enroute to Glacier National Park. Once i learned the "don't exceed 27 psi MAP" syndrome, i was able to go back and forth across the Rockies, plus play on the Banff-Jasper highway plus drive all the way up Mt Baker in Washington (etc etc) with very few dropouts.

So: yes, i modified my technique (but not by much) ... but i'm very rarely a pedal-to-the-metal driver in the Sprinter (since it's my wallet or back-on-the-creeper if things break).

--dick (ScanGauges help)
 

Bobnoxious

Deplorable and adorable.
Gosh, not intending to be confrontational, but why is it necessary exert unnecessary engine stress to merely to maintain 70 MPH on an incline? How about staying to the right and drive at less-stress inducing 60 mph?

Many things can trigger Limp Home Mode, like a sensor briefly out of its happy Zone.
 

Bobnoxious

Deplorable and adorable.
I am guilty as well. Have you ever noticed that people inpart small accelerator pedal oscillations. I first noticed it with my grandmother. I have caught myself doing it, my wife does it.
 
I hate to ask because my lovely wife was driving, but is it possible to trigger a boost shutdown by your driving habits? At the time it shut off, we were on a long upgrade in heavy traffic and she was trying to maintain 70+ mph. I suspect the pedal was mashed to the floor much of the time alternating with very brief instances of no throttle pressure at all.
No worries. :thumbup:

I think the Sprinter diesel has a throttle plate (most diesels do not).

Anything between the turbocharger's compressor wheel and the throttle plate, can be impacted by snapping the throttle shut from wide-open throttle. Snapping the throttle shut is not "wrong", it's just that it can impact things.

What happens is that air, which has mass and therefore inertia, and is also "springy", gets pushed down the intake tract by the turbocharger's compressor wheel, which is not directly connected to the engine- it's just being pushed along by the exhaust-driven turbine wheel. At wide-open throttle, with the engine speed up, and full boost happening, the turbocharger is spinning about as fast as it's ever going to, and a lot of air is being shoved down the intake tract by the turbo, when all of the sudden, the throttle is snapped shut, suddenly blocking the air's path into the engine. The air between the turbo and the throttle plate is already compressed, and it's moving towards the engine at a pretty good speed, but it has nowhere to go. And the turbocharger is still trying to push more air down the intake tract. The air will then "bounce" back and literally stall the turbocharger to a stop, often making a noise that sounds like flatulence.

That's why turbocharged race cars use blow-off valves located between the turbo and the throttle plate, so that when the throttle is momentarily closed during upshifts, the excess air that bounces back is vented out the blow-off valve, allowing the turbocharger to continue spinning, which allows it to accelerate into boost more quickly when the throttle is opened again after the shift.

If a vehicle is going to spring a boost leak, it's probably not going to happen at wide-open throttle / max boost- it's probably going to happen when the throttle is snapped shut FROM wide-open throttle / max boost.

So again, it's not "wrong", and it doesn't require modifying a driving behavior, it's just something to be aware of that can happen.

Hope that helps... :thumbup:
 
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Gsand31415

Guest
Thank you all!

Hey Bob-
I haven't broken my better half's habit of pedal-to-the-metal left-lane driving yet in our 48 years together, but perhaps this episode might convince her to change her ways with this vehicle, at least. My late father (also named Bob, and your handle would have fit him to a T) also nagged her for decades to no effect.
 

autostaretx

Erratic Member
I think the Sprinter diesel has a throttle plate (most diesels do not).
No, the NCV3 3.0L diesel does not have a throttle plate. apparently it does... (see 98Firebird)

It does have "swirl valves", but they just block one of two pathways for the intake air to reach the cylinders. They're closed at low rpm to increase the "swirling" of the air through the remaining port (the "charge port"). Each cylinder has its own "swirl port" and "charge port".

There is no plate (or whatever) blocking airflow through the charge port.
added: it's upstream in the manifold??

The T1N's 2.7L diesel doesn't have swirl valves.

--dick
 
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98Firebird

Active member
No, the NCV3 3.0L diesel does not have a throttle plate.

It does have "swirl valves", but they just block one of two pathways for the intake air to reach the cylinders. They're closed at low rpm to increase the "swirling" of the air through the remaining port (the "charge port"). Each cylinder has its own "swirl port" and "charge port".

There is no plate (or whatever) blocking airflow through the charge port.

The T1N's 2.7L diesel doesn't have swirl valves.

--dick
Just to prevent misinformation, the OM642 aka NCV3 3.0 v6 DOES have an electronic throttle body. Located on the metal intake pipe which bolts to the intake manifolds. It is call out 225 in the parts diagram attached with a part number of A6420900270 for this particular van I pulled the vin from. It is very easy to miss as it is tucked far down in the engine bay near the alternator.
 

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autostaretx

Erratic Member
Dang ... i did a fairly detailed read of the 2007 service manual before posting my answer ...

...back to the book...

--dick (thanks)
p.s. later: my eyes hurt... at least this pass through i did meet the throttle body
(but was surprised to NOT find a paragraph or three chatting about why it's there)
((as in: why this diesel wants one. It was mentioned in gory detail in the PCV and fuel vapors sections))
 
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lindenengineering

Well-known member
Guys
You may ask why do diesel engines need throttle body and a butterfly valve, because it flew in the face of my older tyme understanding of CI engines which were simply controlled by metering the fuel flow. A diesel engine in its purist form doesn't put much importance on stoichimetric operation like a petrol spark ignition engines does.

Air/ fuel ratios of up to 50% are quite a happy medium in CI engines whereas 14,5 to 1 ratio is absolutely necessary to achieve "stoich lambda 1" combustion in spark ignition engines.

So in short diesels engines do not need throttle body and butterfly to ensure efficient operation. It has been employed traditionally though for engine vacuum fuel injection pump governor operation notably on the old 123 MB platform powered OM617, old Leyland and Perkins diesel engine of the 1960's

So you might ask why do some diesel engines like the MB unit are so equipped with the throttle body? Its useful to point out that some diesel engines of the modern era DO NOT have throttle bodies!

The salient reason for a throttle body is emission control and Exhaust Gas Re-circulation (EGR).
In the case of the MB engine, a drive by wire throttle body & butterfly can restrict fresh air from the turbo under low load conditions flowing into the inlet manifold creating a high depression differential, ideal for maximizing EGR gas flow.

Here is some Delphi blurb on the unit and its useful function.

https://www.team-bhp.com/forum/atta...eed-throttle-body-throttle-plate-untitled.jpg

Dennis
 

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