The P1121 diagnostic trouble code (DTC) for the Toyota Prius indicates a problem with the Coolant Flow Control Valve Position Sensor Circuit. This sensor is responsible for monitoring the position of the coolant flow control valve, which regulates the flow of coolant through the engine. P1121 - Coolant Control Valve Replacement (with pics) Discussion in ' Gen 2 Prius Care, Maintenance and Troubleshooting ' started by Stomper88, Jan 24, 2012.
Learn how to fix the P1121 error code that indicates a malfunctioning coolant flow valve in your Prius. The web page explains the function, location and replacement of the valve, and the possible additional codes related to the coolant system. P1121- can i drive on it? Discussion in ' Gen 2 Prius Main Forum ' started by ericspoor, Aug 26, 2018.
Check engine light on - code P1121 Discussion in ' Gen 2 Prius Care, Maintenance and Troubleshooting ' started by Blackbird, Feb 7, 2010. P1121 Fail fix Discussion in ' Gen 2 Prius Care, Maintenance and Troubleshooting ' started by PrestonH2O, Aug 10, 2025. check engine light: codes p1116 and p1121 Discussion in ' Gen 2 Prius Care, Maintenance and Troubleshooting ' started by Kevin Lester, Mar 30, 2013.
P1121+P1116 Write-Up and Troubleshooting Discussion in ' Gen 2 Prius Technical Discussion ' started by tidesofthesky, Sep 6, 2020. The OBD code P1121 for Toyota indicates an issue with the Accelerator Pedal Position Sensor circuit. Symptoms include the Engine Light being ON.
The cause is typically a faulty sensor or related wiring issues. This problem should be addressed promptly to prevent drivability issues. A possible fix involves inspecting the sensor, wiring harness, and connectors for any damage or poor connections.
Former Toyota certified dealership technician here and owner of a 2009 Prius: Direct from AllData but you can get the same info in a DIY friendly price and better format at Mitchell 1 DIY-Do it Yourself Automobile Repair Manuals 1NZ-FXE ENGINE CONTROL SYSTEM: SFI SYSTEM: P1121: Coolant Flow Control Valve Position Sensor Circuit Stuck.
