Tips for New to Sprinter Owners
http://sprinter-source.com/forum/showthread.php?t=23409

Stoopid Things condensed
http://sprinter-source.com/forum/showthread.php?t=8285

Cheap Tricks condensed
http://sprinter-source.com/forum/showthread.php?t=9255

Check Engine Light DTC MIL Codes List
http://sprinter-source.com/forum/showthread.php?t=5369

Limp Home Mode comments
http://sprinter-source.com/forum/showthread.php?t=7173

Trailer Wiring OEM Harness vs. Light Module
http://sprinter-source.com/forum/showthread.php?t=7328

Tools – Quality, Special, Dodge, MB, Mercedes, Hose Clamp
http://sprinter-source.com/forum/showthread.php?t=10485

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T1N’s go up to and including 2006 model year except for some RV conversions. Before anyone that’s looking to buy a T1N continues I recommend you read the Sprinter Wiki link created by Sikwan (in the blue bar above).

There is a danger in highlighting some of the problems associated with the Sprinter and directing people to the various threads discussing those problems. It is easy for it to appear that ALL Sprinters have problems. I’m very happy with my 2004 used Sprinter with 225,000+ miles. I have had very few problems with my Sprinter (knocking wood). There are many happy Sprinter owners that never post in forums. The good news is that these forums are invaluable for DIY, helping to resolve problems, and general information.

The following are some things I have learned from various forums about used Sprinters. These are in no particular order. Most engine comments refer to the diesel engine, not the less common gasoline variety. I would hope others will add posts to make this write up more helpful for anyone looking for a used T1N. Perhaps specific comments related to the various RV brands and installed conversion equipment would help?

Injector black death leakage. From what I gather the fuel injector hold down bolts get loose or the seals erode…. for whatever reason and the injector seals begin to leak. This allows combustion products to escape and build up. This is easily inspected by pulling the plastic cover that shields the injector and glow plug assemblies to inspect for discoloration or black lava like deposits around the injectors. Black lava indicates major failure. Pouring a bit of soapy water on the injector bases will show bubbles if it is in early stages. (Spritzing window cleaner won’t work… don’t ask.) This may be an expensive thing to repair. Dealerships will typically replace the head for broken hold down bolts (if they break). Doktor A has a more reasonable repair which can be performed without removing the head.

Link related to injector failure and inspection:
http://sprinter-source.com/forum/showthread.php?t=3326

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2011/09/12 edit:
Injector seal leakage is not a reason to totally dismiss buying a Sprinter. If the mileage isn’t too high just replacing the bad seal may be a good response. Given very high mileage you might consider replacing all injectors because a bad injector can lead to other more major problems. Injector/seal replacement is very possible DIY.

A recent thread in which Doktor A replies to indicate that “Black Death” can look very bad, but may actually just be one injector leaking.

Looking at buying, and is this the black death?
http://sprinter-source.com/forum/showthread.php?t=17596

My experience changing injectors DIY. What happened to me is probably as bad as it gets. Others have changed seals with little problem.

Remove Pull Replace Install Change T1N Fuel Injector 
http://sprinter-source.com/forum/showthread.php?t=16068

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Glow plug failures. The glow plugs themselves are not expensive, but they have a history of seizing into the head and making replacement a major repair.
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2011/02/15 edit: I feel there is good news related to glow plug removal. Mine came out without any real problems. This thread has what I did for removal. YMMV.

My Experience Changing Glow Plugs
http://sprinter-source.com/forum/sho…&postcount=141

http://sprinter-source.com/forum/sho…&postcount=142

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The Engine Control Unit (ECU) or ECM Engine Control Module is designed to monitor the glow plugs and related control circuit. It is not uncommon for the monitor circuit to show a false fault in the glow plugs. Glow plugs should never be repaired/changed based only upon the ECM fault information codes. There are tests which can be performed to check the glow plugs. Glow plugs may not be critical if you never use the diesel in very cold temperatures. It is reported that the glow plug fault indications are more reliable in the NCV3 models.
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2011/02/15 edit: It is possible to modify the glow plug module and correct most failures by adding wiring and individual glow plug fuses. This helps to avoid an expensive parts replacement.
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Link related to glow plugs:
http://sprinter-source.com/forum/showthread.php?t=743

Having the ASSYST option to help with maintenance schedules is a plus. The ASSYST monitors mileage, oil condition, and other Sprinter functions to help determine what maintenance intervals are appropriate for your use. Not an essential option, but nice to have.

Link related to ASSYST:
http://sprinter-source.com/forum/showthread.php?t=1299

The Sprinter remote door locks can be troublesome. Make certain they are all in working order. Sometimes the repair is an easy cleaning of the door contact units, but not always.

Turbo Resonator 2004 – 2006. Many people recommend that the heavy RV conversion Sprinters install a Riordan turbo resonator replacement. On heavily loaded vehicles there is a history of OEM plastic turbo resonator failures before the Q5 modified resonator. It is probably best if you have a Q5 version of the resonator. They come with a Q5 sticker that may still be on the resonator. A new plastic OEM resonator is around $50.00 for the part. A Riordan aluminum replacement is about $140.00 for the part. Installation is not a bad DIY given the correct tools.

Sprinter NAG1 transmission.
2010/10/19 edit:
The comments regarding the NAG1 transmission below may be a bit out of date in some respects, but I think still basically valid. My more recent ideas and comments regarding the NAG1 transmission can be found near the middle and end of this more recent post. It is my opinion only.

http://sprinter-source.com/forum/showthread.php?t=13215

The Sprinter NAG1 transmission seems to be sensitive to having proper fluid and proper level?? Try to verify that the proper Mercedes Benz (MB) approved transmission fluid is installed. From Dodge the approved fluid is Crossfire/Sprinter in a black plastic bottle. Even with OEM at this time there are 3 versions of fluid. You want it to at least meet the MB spec #MB236.12, or the newer MB236.14 is even better. There are not many common brands of transmission fluid in the USA that meet the MB specs for the NAG1 transmission. ATF+4 is not correct. Even with proper fluid the NAG1 has a Rumble Strip Noise (RSN) quirk which is a light chattering vibration under low loads. I believe the general consensus is that RSN is an annoyance, not a mechanical problem as such. A heavy shudder around 2000 RPM under load probably indicates that the transmission fluid may be in use beyond the required change interval. The heavy shudder is cause for concern. Doktor A has an inexpensive cure for RSN.

Check the metal transmission lines for rusting. My 2004 lines were beginning to rust near the radiator. I smeared grease on mine to help halt the rusting. Others have reported similar rust on older Sprinters.

Some links related to the NAG1 transmission are here:

http://sprinter-source.com/forum/showthread.php?t=5027
http://sprinter-source.com/forum/showthread.php?t=2557
http://sprinter-source.com/forum/showthread.php?t=2476

Check that the heater fan works on all speeds. The heater resistor commonly fails. The indication of failure is that only high speed will work on the fan. Not a big deal, but worth checking. The heater resistor is about $40.00. Installation is a DIY project. No special tools required.

“If the fan works in all speeds [and flow is still low], it is not the resistor pack.
Instead, most people dont know there is a cabin air filter installed under the hood that never gets changed and causes a lot of air restriction.” credit to Skydiver007

Related link here:
http://sprinter-source.com/forum/showthread.php?t=2646

Driveshafts and universals. Make certain that a mechanic checks the driveshafts and universal joints for problems. The driveshaft and universals are only sold as a complete assembly by the dealers. Unlike most USA made vans this is a fairly expensive repair. There is at least one company that retrofits Sprinter drive shafts and sells them on a core return basis. After that the universal joints can be changed out individually. This is not an endorsement of that repair route. I’m just pointing out that it’s an option to buying a new driveshaft assembly.

Fuel line clips. Inspect the fuel line clips are still holding the fuel lines in place. The clip failure is not an expensive repair, but worth checking. If the plastic lines are flopping free they can wear through and begin leaking. I repaired mine by using black cable ties to secure the plastic lines back up into the remnants of the broken clips.

Please feel free to add posts and information. I hope this helps to start a flow of information. vic