P0121 on Toyota Vitz (SCP10): Throttle position sensor range / performance

Short answer: P0121 means “Throttle position sensor range / performance”. The car’s computer has found a fault in the Engine - throttle system and turns on the Check engine light (MIL). First check: check sensor voltage while opening throttle slowly.

Code

P0121

System

Engine - throttle

Dashboard light

Check engine light (MIL)

Also sold as

Toyota Yaris, Toyota Echo (XP10)

Applies to

1SZ-FE (by platform)

Confidence

medium (Toyota Echo 1999–2002 factory diagnostics, same XP10 platform; not confirmed on JDM 1SZ-FE)

Source

carmanualsclub.com

Likely causes

1. Throttle position sensor

What to check, in order

1. Check sensor voltage while opening throttle slowly
2. Replace sensor if signal is not smooth

Related on this car

• All fault codes for this car
• Warning lights
• Where the parts are (parts map)
• Common problems

Same code on other cars

• P0121 · Toyota Passo (1st gen)
• P0121 · Toyota Corolla (11th gen, E170)
• P0121 · Toyota Corolla (10th gen, E140)
• P0121 · Honda City (5th gen, GM2)
• P0121 · Honda Civic (10th gen, FC)
• P0121 · Suzuki Wagon R (Pakistan, K10B)
• P0121 on all cars compared

← P0120/41 P0125 →

Clearing the code does not fix the fault. If it comes back, the problem is still there. For brakes, airbags and steering, see a trained mechanic.