P1123 TOYOTA Possible Causes
- Coolant flow control valve
- Faulty coolant flow control valve position sensor
- Coolant flow control valve position sensor harness is open or shorted
- Poor electrical connection in the coolant flow control valve position sensor circuit
- Faulty engine control module (ECM)
How to Fix P1123 TOYOTA Code?
Start by checking the “possible causes” listed above. Visually inspect the corresponding wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
Possible Symptoms
Illuminated engine light (or engine service warning light soon)
P1123 TOYOTA Meaning
This system uses an electric pump to supply hot coolant stored in the heat storage tank in the engine cylinder head, in order to optimize engine start-up combustion and reduce the amount of unburned gas discharged during engine start-up. The water valve for the Coolant Heat Storage (CHS) system, located at the heater pipes, controls coolant passages to the engine, heater core, and coolant heat storage tank according to system operating conditions.