The circulation pump has an electrical fault or an open circuit
The car appears to be running fine and is not over heating or over cooling.
The Auxiliary water pump has 12v as soon as the ignition is on and I can feel the Aux water pump running running
I have checked the switch over valve solenoid A0025407097 it seemed ok but changed it for a new unit.
I don't appear to have a relay for the aux water pump in the engine bay .
Has anyone got a wiring diagram or does anyone know what i can or should test next.
Is there a test for the pump its self ??




I have done a bit of research and can not find the answer to my fault code.
The car appears to be running fine and is not over heating or over cooling.
The Auxiliary water pump has 12v as soon as the ignition is on and I can feel the Aux water pump running running
I have checked the switch over valve solenoid A0025407097 it seemed ok but changed it for a new unit.
I don't appear to have a relay for the aux water pump in the engine bay .
Has anyone got a wiring diagram or does anyone know what i can or should test next.
Is there a test for the pump its self ??
Your pump is physically running as soon as the engine comes on. You get a fault code.
Every car being nearly similar and different you will need a VIN schematic to poke at yours precisely.
The ignition ON brings AUX-PP: +12V
A control module grounds a relay when needed.
Controller complains pump circuit is ON.
That is a perfect job for F-SAM to do.
First thing to check is...... clean poor GND nearby!
Last edited by CaliBenzDriver; Mar 1, 2024 at 03:58 PM. Reason: typos
The fault code is present all the time I clear down the codes and it instantly comes back on the next scan.
I will check the local grounds to see if there is any faults thanks
What is a F - SAM




These cars are built to be predictable.
Poor GND are high on the list of troublemakers.
In this case pump runs so it is getting all it needs.
These cars are built to be predictable.
Poor GND are high on the list of troublemakers.
In this case pump runs so it is getting all it needs.
any solutions please can’t seem find an answer




If one read the description of the DTC slowly and carefully :
P260000 - the output for the circulation pump ‘coolant’ has an electrical fault or short circuit.
The OUTPUT, not the pump itself. The Y133 valve/solenoid controls the flow to OPEN OR CLOSE and hence is an OUTPUT
Good video here, 2.2 Diesel engine, but it can be a good example.
Good luck


