So this morning the check engine light came on so I drove it to advance about 10min to check to see what to code was and it came back p1151 and the overtemp problem light came on. I ended up adding about 1.5l of water to the radiator and drove for about 20 min and no overheating. Any ideas as to what could be going on. The car had about 325k I think. Edit. I changed out the inverter water pump about a year ago.
No accidents or leaks that I can find. I am starting to think it actually had a little air in the line. Its the only thing I can think of.
Specifically, it is about the temperature sensed at the outlet of the CHR system. The P1151 is set if the following conditions are successively met: CHS tank outlet temperature during preheating: below 50°C (122°F) (2 trip detection condition); CHS tank outlet temperature during soaking: 30°C (86°F) (or more) lower than that obtained when the coolant was recovered. MONITOR DESCRIPTION The ECM detects a malfunction in the coolant heat storage (CHS) system with the CHS tank coolant temperature, the position of the water valve, the running condition of the engine and the operating condition of the soak timer. The soak timer built into the ECM prompts the ECM to actuate the water pump 5 hours after the HV main system has been turned OFF by using the power switch. The ECM then checks the heat retention condition of the CHS tank. In order to ensure reliable malfunction detection, the ECM detects the CHS tank heat retention malfunction in two ways. Thus, when the following two detection conditions are consecutively met, the ECM determines that the heat retention has deteriorated and sets a DTC. During preheating, the CHS tank outlet water temperature is below 50°C (122°F) (2 trip detection logic). During soaking, the CHS tank outlet temperature is more than 30°C (86°F) lower than that obtained when the coolant was recovered. All the details can be found in the repair manual. Ways you can access the repair manual can be found by clicking here.
