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steve, Mercedes Mechanic
Category: Mercedes
Satisfied Customers: 29
Experience:  meredes van/truck diagnostic certified, main dealer employed
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Mercedes: CDi..the EPC light came on and I..diagnose

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Hi, I have a 2000 ML 270 CDi. I live in Zambia. Recently the EPC light came on and I have taken the car the the local Mercedes dealer to diagnose the fault. They told me that the computer had come up with this code that indicated that it was either the fuel shut-off valve or the HP injector pump. The system described some tests to run in order to determine whether it was the valve or the pump. This they supposidly have done and told me that it was the fuel shut off valve which has now ben replaced. However the EPC light is still on and the dealer is now not sure what the problem could be. They have even changed the fuel saying that the fuel in the tank was bad. They have had the car for four weeks now and I feel like they are messing me around. Any suggestions?

hi there

could you tell me the text for the fault codes they advised you on

every fault code will have a short text with it

regards steve

Customer: replied 8 years ago.
Hi Steve,
I do not have this information to hand I'm afraid. We have a holiday here until Wednesday when I will try to get the codes and text.
ok here from you soon
steve and 5 other Mercedes Specialists are ready to help you
Customer: replied 8 years ago.
Reply to steve's Post: Hi Steve,
I have been down to the dealer now. Here is the lowdown:
The fault code that the diagnostics has come up is P1622-128 Y75 for Electric switch-over valve - status "current and stored" for MB CDi ECU #(NNN) NNN-NNNN

The fault requires a test to be run to check the pressure in the system. If the test result shows and increase in pressure of 0.2 - 0.5bar and then stabilising and engine runs - indicating pump fault. However, if there is no increase in pressure and engine does not run - indicates switch-over valve. The ACTUAL test results were an increase in pressure of 0.1bar (less than required increase to indicate pump fault) and engine runs.

Would this mean that the pressure limit on the ECU needs to be adjusted to allow the small increase in pressure or the pump really is at fault? The valve has been replaced but the fault is still present.

Prior to this I had serviced the car and replaced all the filters. When it came to start the engine, it had to be cranked for a good 30 seconds before the system was bled and the engine statrted. Would this have caused some damage to the pump?

Is it safe to use the car like this as the car runs fine but book says don't rev over 2500rpm with EPC light on.

I really look forward to your help. Thanks

hi there

first thing i would do is cheak the fuel sysyem for air

i have had vehicles that have had pumps,injectors,valves replaced and it has only been air in system that was the fault

at about 1500rpm cheak every clear fuel pipe on the engine use a torch if needed for air bubbles or movement

if there are some present cheak all pipe fittings and replace fuel filter and all valves , fittings on fuel filter

as per winding over for long time after service some times it can damage pump but normaly it.s ok

let me know how you get on

regards steve

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Customer: replied 8 years ago.
Thanks Steve,
I will pass this information on to the dealer. Once we have eliminated this as the problem, I will let you know how we get on. Thanks so far.
Customer: replied 8 years ago.
Hi Steve,
Just to keep you in the picture. The dealer has looked into this and "thinks" that the air is the problem - oming into the filter from the inlet. I am now waiting for them to eliminate this so we can know for sure. All the best and thanks for your pateince - things happen at a snail's pace here!


hope we get there and you get it fixed

regards steve

Customer: replied 8 years ago.
Hi Steve,
I have now been told that the air is fixed but EPC is still on. Revs not pulling above 2500/3000 .... They say the pump now.
Customer: replied 8 years ago.
Hi Steve,
Thanks for your help. The car has finaly been fixed with a new pump. It turns out that the fuel here has a very high sulpher content and this is the reason that we have been given for the pump wearing out and not reaching the required pressure.

Thaks for your help.

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