Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P1121: Throttle Position (TP) Sensor Signal Lower Than Expected
Turn ignition switch ON (II). Using scan tool, check throttle position. If throttle position is 14.4% or more when throttle is fully opened, problem is intermittent. System is okay at this time. If throttle position is not 14.4% or more when throttle is fully opened, replace TP sensor.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.