HiBread Posted November 23, 2020 Report Share Posted November 23, 2020 Hi. Over the years I've learned a lot from this website and this is my first post. The wrench light on my 2013 CMAX SE (92K miles) turned on. The car drove normally for several miles but then the Coolant Overheat light came on. Within a short time the car went into fail-safe mode (limp mode) so I pulled over and had it towed home. Both coolant levels are fine. All the hoses look okay. No leaks. Nothing is blocking the radiator and the radiator fan works. I read a bunch of posts here and decided to start with changing the Engine Coolant Temp sensor. I also changed the air filter while I was at it. I test drove it and the engine sounds great and the car runs fine. Unfortunately, after a couple of miles or so, the Coolant Overheat light turned on. I did not drive it long enough to go into fails-safe mode. I retrieved the DTC codes from the dash (see attached images). DTC C41282 X and C46B86 X. Does anybody here know what the problem might be? Thanks for your time. Quote Link to comment Share on other sites More sharing options...
plus 3 golfer Posted November 23, 2020 Report Share Posted November 23, 2020 (edited) Sounds more like thermostat is closed. When you get the overheat condition, feel if the radiator is hot. If not extremely HOT it’s likely the thermostat. Also, it could be the electric water pump. When this happens, you can set the set point temperature to max heat and likely lower coolant temperature. The DTCs in ETM appears to show only codes related to the instrument cluster / dash components. See this post. Edited November 23, 2020 by plus 3 golfer Quote Link to comment Share on other sites More sharing options...
HiBread Posted November 23, 2020 Author Report Share Posted November 23, 2020 Thank you, plus 3 golfer. I'll give that a try in the morning. Quote Link to comment Share on other sites More sharing options...
HiBread Posted November 24, 2020 Author Report Share Posted November 24, 2020 I already had a new thermostat so I went ahead and swapped it. I tested the old one, and the new one, in 190 degree water and they both opened up. Darn. Test drove it. The wrench is still on but I expected that. After a few miles the Engine Coolant Over Temperature came on again. I set the dash to show coolant temp and it showed 81 C (177.8 F). The coolant level is topped off and reads fine. Is there a way to test the water pump without taking it out? Any other suggestions? The dealer is backed up for a couple of weeks! Thanks. Quote Link to comment Share on other sites More sharing options...
plus 3 golfer Posted November 24, 2020 Report Share Posted November 24, 2020 (edited) Do you have a Hybrid or Energi model? The attached OBD System Manual indicates that if the Cylinder Head Temp exceeds 270 F, a DTC is set (wrench) and the car operates in fuel shutoff / fail safe cooling mode (limp mode). ECT is a derived value from the CHT sensor. I have operated my C-Max Hybrid at 230F ECT + with no DTC. We really need to know what DTCs are set. I believe Autozone still reads DTCs. I have said this many times the FORScan app is well worth it for troubleshooting issues. FORScan for Windows has output control and may be able to operate the water pump. When I have time I’ll see if the pump control is available. FORScan Lite versions have several PIDs for the pump including rpm but not control functions yet. https://forscan.org/home.html OBDSM1700_HEV.pdf Edited November 24, 2020 by plus 3 golfer Quote Link to comment Share on other sites More sharing options...
HiBread Posted November 24, 2020 Author Report Share Posted November 24, 2020 Thank you for the document. I see where it mentions > 270. I have downloaded FORScan. I will order a bluetooth (or wired connector) and report back. ? Quote Link to comment Share on other sites More sharing options...
HiBread Posted December 19, 2020 Author Report Share Posted December 19, 2020 Update: Replaced the water pump and it's back on the road. ? Lacienega and grege 2 Quote Link to comment Share on other sites More sharing options...
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