View Full Version : Injector sensor problem

09-06-2013, 01:45 PM
Hi from France, My 1998 Sprinter 412d refuses to start even wih a sniff of ether. On diagnosis the fault reader says code 1223 which is INJECTOR SOLENOID POSITION SENSOR .
Can anyone please tell me where this is located or how to solve my problem without parting with large amounts of money at the " Mainstealers "
The van cranks vigorously and there is fuel up to the injectors .Any advice would be appreciated. Don

09-06-2013, 09:17 PM
P1223 doesn't sound familiar to me, are you using a Mercedes specific diagnostic tool?

If so and it really is the injector "needle lift sensor", the only cure is a new injector, make sure you are sitting down when you get a quote!

I have a bit of a problem with the description "injector solenoid position sensor" though, that sounds like a code for a CDI injector which yours aren't (not opened by solenoids). The same code may well be used for the needle lift sensor in our injectors as for the solenoid position sensor in a CDI injector, but I would try to get a confirmation of the meaning in relation to your van before doing anything drastic.

As a further check, find the cable that runs to the injector with the sensor (it is one of the 2 mounted on the intake manifold), unplug it and measure the resistance accross the pins on the injector side of the connector. The resistance should be 103 ohms, if it isn't very close (maybe +/- 5) your sensor is dead. The sensor injector can't be repaired - not even with a new nozzle, apparently it never works afterwards so it always has to be replaced.

For my 1996 the injector part number is different to yours and probably getting rarer, I had to buy the sensor injector earlier in the year and it was the best part of 500 - from a diesel specialist, not a Merc dealer. One of the later part numbers, possibly the one for a 1998, does come up new on ebay occasionally - they tweaked the opening pressures slightly and changed the leak off fittings so I couldn't just get one of those instead. Good luck, I hope the code turns out to be misinterpreted!

Thinking about this some more before hit reply......
My van started OK when the sensor was down, it just ran badly.
The only times my van wouldn't start at all, but with diesel getting to the injectors were:
a) when the cylinder head cracked - wouldn't start hot, bit after cooling down for an hour it would start again. Obviously as soon as I worked out it was the head I stopped trying to start it.
b) after I changed the head the van died on me on the way to my brothers wedding. It was delivering fuel to the injectors but not at high enough pressure to open them (like I say no solenoid, just two stage spring loaded injectors on these). Turned out to be the fuel temperature sensor in the fuel pump itself - fortunately the garage I ended up at was able to change that sensor relatively easily and I was back on the road by lunchtime, just a shame I got to them as they closed on the Saturday so it was the Monday lunchtime....

In case B it fired on ether but would only run for a few seconds because the injector nozzles weren't opening. The ECM obviously can't stop the mechanical part of the pump from pumping, but it can stop it pumping enough to make the nozzles open.


09-06-2013, 10:18 PM
Hi Jim and thanks for your input. The code reader is a generic one,I,m in rural France and there aren't,t any Indies about and also the language is a bit of a problem.
I was told by Sprinter owner that P1223 was actually FUEL RACK POSITION SENSOR so as you suggested the first diagnosis could be a misinterpritation.
Whilst cranking there appears to be a very healthy amount of fuel when an injector is cracked open,however the engine refuses to fire even on a sniff of ether. Does this new version of the error code make more sense to you and if so do you know where the sensor is located.
I really appreciate your reply. Thanks. Don.

09-08-2013, 12:07 AM
That is looking quite likely I'm afraid.

The 'fuel rack' is the device in the pump that meters out the fuel. In my anecdote b) the symptoms were quite similar although it was the fuel temp sensor that was down. The pump is rotary and sends a shot of fuel to each outlet in turn, but the ECU can control how much fuel is in each shot by altering the fuel rail (like a syringe in the middle of the pump with different outlets that open up depending on the position of the engine). The injectors open at 190bar (from memory - they are 2 stage and open fully at about 400bar), so if there isn't enough fuel in the shot to reach that pressure within the stroke of the pump, the injectors won't open. You are probably wondering why it wouldn't shut off all fuel, and I think this is because the extra 'leak off' from the injectors is used to lubricate the pump so the minimum setting just sends enough fuel out to lube itself but not enough to open the injectors - which is why you appear to have plenty of diesel coming out when you crack the unions, but the van won't start.

Obviously in my case because the ECU didn't know the fuel temp it disabled injection to be on the safe side, in your case it doesn't know how much fuel is being injected so it has disabled injection, but due to the way the system works, there is still fuel coming through, just not enough for injection.

What to do?
Well the sensor is inside the fuel pump, that means you need to somehow get to a diesel specialist that knows about these older pumps, or find a garage that can take the pump off and send it to someone who can fix it (with the proviso that the garage is competent to set up the timing when it comes back). The thing is, I don't actually know if that sensor is replaceable, if not you would be looking at a new pump.....

How deep in France are you?
Kent Diesel Centre in Maidstone are competent with these pumps (it was them that diagnosed and fixed mine), it might be worth giving them a call (08448 152248) to find out if it can be fixed. If you have to get a tow home, since you are from Isle of dogs they are probably the best place to get towed to - I called a lot of garages in Kent and they were the only one even able to plug a 312d in to run diagnostics.

Good luck!

09-08-2013, 09:26 AM
Good Morning Jim, Your advice is very welcome. I,m actually in Central Brittany and to take the van to Maidstone would be about a 400 mile tow so probably easier to go to local MB commercial workshop in St. Brieuc,about an hour away. This makes my wallet very nervous but the cost of getting back to Kent would be considerable what with fuel and the boat etc.
My nearby market town of Callac has several garages one of which has a busy workshop but there,s always that feeling of "out of the frying pan and into the fire" , as you say getting into taking pumps off and timing and re- fitting them might be a bit much for small garages.
The other potential "fly in the ointment" is that the van is an "A" class Hymer which if you can visualise it has a very small opening to the engine compartment making access very tight.
Anyway I ,ll let you know how I get on. Don

09-09-2013, 11:05 AM
The other potential "fly in the ointment" is that the van is an "A" class Hymer which if you can visualise it has a very small opening to the engine compartment making access very tight.

Yes, A friend has a hymer, not sure what chassis it's on but they don't have much of a bonnet and even flatter front than the sprinter.

Good luck!

10-13-2013, 11:20 AM
Hi Jim , You were right,1223 was "fuel rack position sensor" so got the local guy to remove the pump and have it re furbished by a nearby injection specialist.Local man re fitted and timed it up and it' s running really strong.
Total bill was Eurus 911.00 including recovery of 100.00 E . Local man's labour was 45.00E per hour so it could have been a Lot worse.
Thanks for your help. Don

10-14-2013, 03:18 PM
Good to hear you got it going again. Shame it cost a bit :(