Crossfire Coolant Leak & Engine Heat Needs Emergency Fix

Had similar symptoms on a 2007 Chrysler 300C with the 5.7L engine. The control unit was showing multiple diagnostic trouble codes related to temperature management. After thorough testing, the issue traced back to faulty wiring harness connections at the ECU. The root cause was corrosion in the CAN bus connectors, creating a communication fault between the engine control module and cooling system components. The corroded pins prevented proper signals from reaching the cooling fan control unit, leading to intermittent fan operation and overheating. The repair required: Complete inspection of the wiring harness, Replacement of damaged connector pins, Resealing of the control unit connection points, System-wide diagnostic reset This was a serious issue that could have led to engine damage if left unaddressed. The connectivity issue affected multiple systems since the control modules were not communicating properly. The coolant leak you describe likely stems from excessive pressure due to improper fan cycling. Recommend having a qualified technician perform a full diagnostic scan focusing on the control module communication. The wiring harness should be thoroughly inspected, particularly around connection points where moisture could enter.

Thanks for sharing those details about the wiring harness issues. Just curious, what did the total repair cost you? I ended up having eerily similar trouble with my Crossfire last winter. Got it fixed but wondering if I overpaid compared to others. Also, has everything been running smoothly since the repair? My control module has been acting up again recently showing new diagnostic trouble codes, so hoping your fix was more permanent.

After getting the control unit communication error properly diagnosed, the repair was relatively straightforward. The technician found and fixed a faulty cable connection causing the data link issues, which cost 95€ for the repair. Since fixing that connectivity issue six months ago, the CAN bus system has been working flawlessly with no new diagnostic trouble codes appearing. The communication fault between modules was completely resolved once the damaged connector was repaired. This kind of lasting fix is typical when the root cause is properly identified and addressed. If your control module is showing new codes, I recommend having the wiring harness connections checked again, particularly around areas exposed to heat or moisture. These communication problems often trace back to deteriorated connections rather than the modules themselves.

Thanks for the advice. After dealing with those control module issues and engine overheating problems, I finally got it sorted at a new shop. The mechanic found corroded wiring causing a communication fault between modules, similar to what others described. Total repair came to 320€ including diagnostic work and parts. The shop replaced damaged connectors in the CAN bus system and cleaned up several corroded pins that were causing the connectivity issue. After a full system reset, the check engine light cleared and temperature readings returned to normal. No more coolant leaks or software glitch warnings for the past 3 months. Really glad I asked here before spending more money at my old mechanic who kept replacing parts without fixing the actual communication problem. The control unit is working perfectly now and engine temperature stays steady even on longer drives.