P106 with no symptoms

Hi all. First post on here. Having an issue with a 2005 Freighliner sprinter I just bought with 94k miles. The van runs great but I have this issue where the CEL will illuminate and throw p0106 after cranking before the engine starts. I can shut down, clear the code and drive 250 miles with no CEL. Then let the van sit overnight and I get p0106 again upon cranking. Also I'm unable to erase this code with my cheap scanner. I erase the code and the CEL goes out but the scanner still recognizes the fault being present. The snapshot function on said cheap scanner showed the MAP sensor at nearly 28inhg at the time of the fault(s)which is what it will read unplugged.
Things I've tried: checked charge air hoses, resonator for leaks. Saw a bunch of soot around the MAP and IAT sensor housing so I pulled the MAP sensor and found the oring was cut in half. Replaced with a 4mm oring with no change. Question is; do these Bosch Map sensors have a history of failing in this way? If it was the sensor or wiring I would think I would get the CEL all the time. Likewise if there were truly a charge air issue I would think the van would run like crap. My issue appears to related to cranking which just sounds wacky to me. Any info or help would be appreciated.

Well, P0106 isn't listed as a valid code for a 2005 Sprinter.

(complete code list: http://www.diysprinter.co.uk/reference/T1N_CompleteSprinterFaultCodeGuide.pdf )
((and also in the Powertrain documents for the 2004 and 2006 at http://www.diysprinter.co.uk/reference/ ))

P0106 as a "generic code" claims that the barometric sensor is out-of-range ... but that it NOT how the Sprinter would tell you about it. It would be a P1105 with a sub digit for high or low.
(if it really WAS the barometric sensor ... one of them is on the ECM board itself. Don't go there)

Before you waste more money on random parts, pick up a Sprinter-smart scanner like the AP200 from Autel $69.
(there are threads about in the group's "scanner" sub-forum)

The MAP sensor doesn't commonly fail. Underboost would be a P0299 code.

The T1N Sprinter (like your (and my) 2005) doesn't let a generic OBD scanner talk directly to the sub-modules... so the "clear" is only affecting the ECM, not whatever module is really complaining.

Visit http://www.diysprinter.co.uk/reference/
and http://diysprinter.co.uk/reference/T1N_service_scans/ for MUCH more background information.

--dick

Welcome!

“Seems related to cranking” suggests a weak battery or a corroded ground connection?

There are two major grounds involved in cranking (and a bunch of equally important minor ones...)
One is where the battery negative cable is bolted to the firewall, the other is the engine’s ground strap that bridges the rubber engine mount below the fuel filter and brake booster. Cleaning these ground bolts every couple of years keeps them free of corrosion and will save you grief chasing random symptoms in the engine (and other) electronics.

Clean them by removing the stack of wires from their screw, wire brushing all the contact surfaces until they are bright and shiny, re-stacking them, and bolting tightly. Then give the assembly a healthy shot of battery terminal spray wax to keep moisture out - one spray can probably lasts a person a lifetime?

There are also ground lugs behind the headlamp pods, under the dash hump, two under the driver’s seat... browse section 8W of the service manual Dick pointed to:
http://diysprinter.co.uk/reference/2006-VA-SM.pdf
Eliminating grounds as a possible cause of electrical problems is well worth the time spent, especially on a 15 year old van.

Good luck! Hope this helps.
Remember to follow up here with what works or with more questions.

-dave

Great info, and thank you both so much for the quick and thorough replies. Scanner is definately the next step. As I have read on these forums, they are a vital component of Sprinter ownership. Good call on the ground cables, I pulled the engine grounding strap which looked terrible and cleaned it and I'll do the others today. While I wait for the scanner, anything else to check? I was going to pull the ambient air sensor and just hit all the air related sensors with some contact cleaner just to check that box. But without any other symptoms engine wise, I'm at a loss of what else might be causing this. Oh, almost forgot, only other symptom I have that I'm almost certain is unrelated is a small squeal when I accelerate passed 3000 rpm. I've read about exhaust gasket failures and manifold studs being loose as a possible cause. So I'll check that too and report back. Again, thank you both for the responses and info. Great community on here.

Unless the ambient air sensor is giving you an actual code/out of spec reading, leave it alone. I unplugged mine as carefully as I could and the plastic tab still managed to break. I zip tied it back in and that proved intermittent so in the end i had to make a plastic wedge and god knows what else to make a good connect.

Thank you Patrick! I was literally walking out to pull that bad boy when I read your response. Leaving that one alone for now. So a small update; cleared the MAP code and drove to the beach to surf the most worthless post- hurricane swell the state of Florida has ever seen. No CEL, got back in th van and started with no CEL. Van sat for 3 hours and then cranked a couple of revolutions more than normal for start up, CEL lit up. I was able to get all the grounds cleaned up. They needed it. Cleared the code and idled for a 10 mins with no code. Going to get on the road this afternoon and run her through the paces. Thanks again for help guys.

Update to my issue; I've found that 2 hours is the amount of time the van can sit and restart without throwing the CEL. Any amount of time longer than that and it sounds like it takes 2 or 3 more revolutions to start and the light comes on. Yesterday after driving around awhile I got the battery load tested and it was good and Battery voltage while running is a little better than 14v. As Dave suggested I'm wondering if the battery is getting weak, but since I had it tested after driving around, it load tested ok. Condition of the battery and terminals looks good but I have no history on the battery at all. Question; since these sensors all need some kind of reference voltage and since my issue appears to be related to length of time the van sits/cranking during start up, is it possible that my battery is mearly masquerading as good based on the fact that I load tested after it had been charged by the alternator for awhile? The van starts and runs great so this issue is small potatoes compared to others on here but I really appreciate the help.

Almost (if not) all of the sensors reference themselves against regulated voltages that are supplied by the ECM.
Some use 5v, some use 12v. Some are three-wire devices which create their own references internally.
(you can spend days reading here: http://diysprinter.co.uk/reference/T1N_service_scans/ )
The "common mode diagnosis" pages in there show the reference voltage distribution network.

My 2005 will start with the battery being dragged down to 11.3 volts by the glow plug and starter demand.
The Sprinter will throw a B1010 code if it thinks the voltage is too low (and almost all T1Ns have that code stored).
The B1010 does not appear to cause a CEL.

--dick

Thanks Dick, great info. So a low or weak battery is out. Scanner should be here this week and hopefully will shed some light on what's going on. I will report back promptly. Many thanks for the information and responses.

Alrighty, got my scanner finally (Thanks Dick) and pulled the following codes:
2355-001 CDI control module is defective
2817-001 engine off time
2025 004 intake air pressure sensor voltage high
And P2882 refer to vehicle manual.

I cleared the codes and all cleared except for 2025 004.
I'm going to look in the handy fault manual, but any thoughts on what might be happening here? Thanks all.

It could be bad wiring to the MAP sensor (screwed into plastic section between two fat pipe on battery side of radiator)
The IAT sensor is held into the pipe by its plastic clips ... the pressure sensor is flat against the pipe.
Check the wiring path.

Labeled "boost pressure sensor" here:



--dick
2006 service manual: http://diysprinter.co.uk/reference/2006-VA-SM.pdf
2004 service manual: http://www.diysprinter.co.uk/reference/2004-VA-SM.pdf
Additional manuals, fetch the 2004 powertrain manual, too: http://www.diysprinter.co.uk/reference/
and don't miss all the deep-info goodies here: http://diysprinter.co.uk/reference/T1N_service_scans/

Sorry it took so long for me to update. Changed IAP sensor. Issue solved. Thanks for the help all.