Hi there I search the threads for a resolution to this fault code P0481. I don't like Engine Failure warning lights and beeps. I've been struggling to fix the problem. I quickly assumed that the relay mounted to the twin fan assembly was at fault but having measured it with a digital volt meter and even tried a second one that does not seem to be the problem.


I've used the Fiat OBD Diagnostic controller to trigger the low speed fan, that works fine. Both #1 &#2 fans run up to a low speed. However when I trigger the 2nd (hi speed) fan then nothing happens. The radiator mounted assembly relay does not click. The circuit is not activating it. I've tried manually pushing the relay coil contact with my finger and indeed the 2nd speed fan current causes the two fans to run at high speed.



So I have started tracing the control wires back to the engine bay mounted fuse box, the terminate in a connector under the box before then running back to the loom bundle. I cannot find a physical break in them.


So the PO481 code is correct, the 2nd speed fan circuit is not working but what do do about it... I am at a loss. I have checked all the fuses in both boxes and the relays pertinent to the fuses in engine bay box.


If anyone has anyone has ideas you are welcome to suggest...I guess I could mount a manual control switch to trigger second speed but that would be a bodge...

Mmm, well 3 hours of checking all earth points and continuity made no difference. The fault is still there, high speed solenoid is not being activated. Could be wire back to the ECU or ECU itself. I wonder if anyone has a pinout diagram the for Doblo 1248cc diesel (2008). Thanks Paul

Bought a new fan controller relay (mounted to the radiator assembly) The fault is still there. Fiat ePer software cannot trigger the hi-speed fan, must be a control circuit failure, another relay or wire discontinuity or perhaps even an ECU circuit failure but I guess that is unlikely?

pachadwick1 said:

Bought a new fan controller relay (mounted to the radiator assembly) The fault is still there. Fiat ePer software cannot trigger the hi-speed fan, must be a control circuit failure,

Click to expand...

Eper software..??
You lost me there..

Sorry, I got confused, I meant FiatECUScan.

Fixed it, seems that continuity was poor, high resistance on the wire number 7 from the ECU to the relay assembly, I had to put a "jumper" in and it was fixed. This was after rpelacing all the relays without resoltuion. A pretty scary fix really.