Solved! 2003 Benz Sprinter T1N P1470-4 Turbo Vacuum Valve Diagnosis

2003 Benz Sprinter T1N loss of power solved with Autel MD802’s assistance.

 

Here we go for details.

 

Car model and symptom:

A loss of power in my 2003 Benz Sprinter T1N with no CEL (aka MIL) illumination.

 

Sprinter scanner to use and fault code:

Scan with my Autel MaxiDiag Elite MD802 scanner:
Read fault code: P1470-4 Charge pressure control valve – Cable has Short circuit to Positive.

P1470 4 Charge Pressure Control Valve 01

 

What I did:

Testing with a multimeter showed 12 Volts on the Brown wire which I always thought was Ground on a Mercedes.

 

I inspected the harness as far as possible and could see no evidence of any damage.

I got to thinking that if it wasn’t a wiring fault how could the fault code report “Short to Positive”. The answer seemed to be that if the valve had too low a resistance it would then draw too high a current and hence may flag up the “Short to Positive” code.

I then found a thread… and in Post Dr A said ” A functional 612 vacuum solenoid will read approx. 14.0 Ohms when using a quality multimeter, zeroed to compensate probe resistance.”

P1470 4 Charge Pressure Control Valve 02

 

A final check of the wiring was to disconnect the valve and clear the original code, scanning again gave a new code…

P1470-8 Charge pressure control valve – Cable has Open circuit or Short circuit to ground.

P1470 4 Charge Pressure Control Valve 03

 

To my way of thinking this confirmed the wiring as being OK.

I purchased a new valve (Genuine MB) and this measured 14.3 Ohms so in line with Dr A’s figure. After fitting I was finally able to clear all codes!

P1470 4 Charge Pressure Control Valve 04

P1470 4 Charge Pressure Control Valve 05

I have yet to road test my Sprinter but am confident I have found the fault.

So if you have a code P1470-4 try unplugging the solenoid, you can just reach it below the air filter box, then erase the code and re-scan to see if the code changes to P1470-8. This should confirm that the wiring is OK and the valve has failed.

Finally the easiest way to replace the valve is to remove the RH headlight after removing the grille.

This write up is only applicable to T1N’s with the OM611 or OM612 engines with the Vacuum Solenoid controlled Turbo where the solenoid is located under the RH headlight. (NOT the OM647 with electrically controlled Turbo).

 

Credits to @Cheyenne.

 

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