P0C74-00 : tiny coolant leak or weak pump?
Hi everyone,
I know not many people here have the Renegade/Compass 4xe setup, but I’m looking for any insight from people familiar with the 4xe cooling system or similar hybrid coolant circuits.
I’m dealing with an intermittent CEL on my Jeep Renegade 4xe. The code I eventually found with MultiECUScan is:
P0C74-00 — Motor Electronics Coolant Pump “B” Control Performance
The car drives perfectly:
- no hybrid warning
- no limp mode
- EV mode works
- charging works
- no obvious overheating
- no immediate CEL after clearing the code
Sometimes the code comes back without triggering the CEL right away. The CEL only seems to appear later, after the fault has matured.
I can activate the pump with MES. The pump runs, the coolant level moves in the hybrid coolant reservoir, and the current seems coherent with the PWM.
I also visually checked the auxiliary pumps I could access. They don’t appear damaged, the connectors seem properly seated, and I couldn’t see any obvious coolant leak directly from the pumps.
So it does not look like a completely dead pump.
What I’m mostly wondering about is the hybrid coolant reservoir. I had to top it up maybe two months ago. The regular engine coolant reservoir has never needed topping up. Now the hybrid reservoir seems slightly below max again.
I also found dried orange coolant deposits under the hybrid coolant reservoir, and after driving it was not completely dry underneath. There was still a bit of moisture. The deposits seem to be near the lower outlet/neck area of the reservoir rather than around the cap.
Inside the hybrid coolant reservoir, I can see some marks on the walls. At first I thought they might be bubble traces, but now I’m thinking it could just be condensation or dried coolant marks. The regular engine coolant reservoir does not have the same kind of marks tho.
My main question is:
Could a very small leak or pressure loss at the hybrid coolant reservoir / lower outlet / hose connection be enough to cause P0C74?
I’m wondering if the system could be losing just enough pressure, or possibly drawing in a tiny amount of air, to make the pump performance look borderline to the HCP, even though the pump still runs and the car behaves normally.
Any insight would be appreciated.