Parts for your 2009 Toyota Bb-Throttle position sensors

2009 Toyota bB throttle position sensor: what it does, where it lives, and how to look after it

Based on manufacturer service literature for the QNC2# series bB (Toyota Service Information/TIS: Engine Control – ETCS-i, Toyota bB QNC20/21/25 Repair Manual, Daihatsu K3-VE/3SZ-VE EFI System descriptions), the 2009 Toyota bB uses a throttle position sensor (TPS). It’s built into the motorised throttle body as part of Toyota’s Electronic Throttle Control system (ETCS-i), with dual sensor tracks for redundancy. So the TPS is absolutely relevant to this model and to how smoothly it runs.

On this bB, the TPS tells the engine control module exactly how far the throttle plate is open. Working together with the accelerator pedal position sensor, it helps the ECU deliver crisp response, stable idle, and proper fuel and ignition timing. Because it’s integrated with the throttle actuator, it’s not an adjustable item, and on most sub-models it isn’t serviced separately from the throttle body.

Typical signs the TPS circuit needs attention include erratic idle, hesitation, sudden surging, poor fuel economy, a check engine light, or limp-home behaviour. Common DTCs include P0120–P0124, P0220 and P2135. If any of these crop up, a proper scan and live-data check is the go-to starting point.

As part of routine servicing, it’s smart to:

• Inspect the throttle body for carbon build-up and clean it with throttle-safe cleaner (avoid soaking the shaft or motor cavity).
• Check the TPS/throttle body connector and harness for corrosion, oil wicking or poor pin fit.
• Verify the throttle angle and accelerator pedal signals agree in live data.

If replacement is needed, most 2009 bB variants require swapping the complete throttle body assembly. Use a new gasket, torque the fasteners correctly, and perform an ETCS/throttle position initialization with a scan tool. If a scan tool isn’t available, an idle relearn (fully warm engine, all loads off, let it idle for several minutes) usually stabilises things, but a proper initialization is best practice.

Quality matters here: a genuine or reputable OE-equivalent throttle body helps avoid repeat faults. After fitting, clear codes, verify idle speed, and road test for smooth take-off and clean shifts. Look after the TPS/throttle body and the bB will reward with tidy throttle response and reliable commuting for many kilometres.

• Where is the TPS on a 2009 Toyota bB?
  It’s built into the throttle body on the intake manifold, paired with the throttle control motor. There isn’t an external, adjustable sensor like older cable-throttle setups.
• Can the TPS be replaced on its own?
  On most 2009 bB variants, no. The TPS is integral to the throttle body and is not service-adjustable, the usual fix is to replace the throttle body assembly and then carry out throttle initialization.
• What symptoms point to a bad TPS or throttle body?
  Rough or hunting idle, hesitation, sudden surging, poor economy, and a check engine light. Fault codes such as P0120–P0124, P0220 or P2135 are common clues and should be confirmed with scan-tool data.