P1121 Throttle Position Lower Than Expected

What does P1121 mean on a Honda?

P1121 — Throttle Position Lower Than Expected. This Honda-enhanced code applies to Civic, Accord, CR-V, Odyssey.

Common causes of P1121

• Carbon buildup in the throttle body holding airflow low
• Worn throttle position sensor giving a low-biased signal
• Vacuum leaks downstream of the throttle body
• Sticking throttle plate or weak return spring on cable throttles

How to fix P1121

1. Compare commanded versus actual throttle and MAP data on an HDS scan tool
2. Clean the throttle body and perform the Honda idle-learn procedure
3. Inspect the TP sensor sweep for dropouts with a multimeter or scope
4. Repair vacuum leaks before replacing the sensor or throttle body
5. Clear codes and road-test including deceleration and idle