Parts for your 2015 Toyota Mark x-Throttle position sensors

2015 Toyota Mark X throttle-position-sensor (TPS): purpose, servicing and replacement

The 2015 Toyota Mark X (GRX13#, 4GR‑FSE 2.5L and 2GR‑FSE 3.5L) absolutely uses a throttle-position-sensor. Toyota’s own technical literature confirms Electronic Throttle Control (ETCS‑i) on these engines, with a throttle body that integrates a dual-track TPS and an electric throttle actuator. See: Toyota Mark X GRX13# Repair Manual, SFI System (2GR‑FSE/4GR‑FSE), ETCS‑i description, Toyota DTC listings covering P0120–P0124 and P2135 (Throttle/Pedal Position Circuit), and Toyota Genuine Parts/EPC notes showing the TPS supplied as part of the throttle body assembly. So, the TPS is relevant and fitted to the 2015 Mark X.

On the Mark X, the throttle-position-sensor tells the engine control module exactly where the throttle plate is at any moment. Paired with the accelerator pedal position sensor, it lets the ECU finely meter air and fuel, manage idle, and deliver smooth, responsive acceleration. Because it’s drive‑by‑wire, accuracy from the TPS is critical for power, economy and emissions.

For servicing, there’s no fixed replacement interval for the TPS. It’s integrated into the throttle body, so faults usually mean replacing the entire throttle body assembly rather than the sensor alone. Tell‑tale signs include erratic idle, hesitation, sudden limp mode, poor fuel economy, or a glowing MIL with codes like P0121 or P2135. A scan with live data is the best first step—look for TPS signal dropout or mismatch between throttle and pedal angles.

• Good practice:
  • Scan for faults at service time, especially if drivability seems off.
  • Clean the throttle body with sensor‑safe cleaner when carbon build‑up is evident. Don’t force the plate by hand.
  • If the throttle body is removed, fit a new gasket, torque evenly, and perform idle/throttle relearn with a capable scan tool.
• When to replace:
  • Persistent TPS‑related DTCs, inconsistent voltage tracks, or confirmed internal sensor failure.
  • Water ingress or connector damage that can’t be reliably repaired.

Owners of a 2015 Toyota Mark X can expect a quality throttle body/TPS to last many years and kilometres, provided air filtration is sound and the intake isn’t contaminated. When replacement is needed, using a genuine or high‑quality unit, plus a proper relearn, keeps throttle response crisp and trustworthy for everyday driving across Australia and New Zealand.

Popular questions

Does the 2015 Mark X have a separate throttle-position-sensor or is it built into the throttle body?
It’s built in. On the GRX13# Mark X, the TPS is integrated with the electronic throttle body (ETCS‑i). In most cases it isn’t serviced separately—if the TPS fails, the complete throttle body assembly is replaced and then an idle/throttle relearn is carried out.

What symptoms point to a failing TPS on a 2015 Mark X?
Common signs include uneven idle, hesitation on take‑off, flat spots, sudden limp mode, or poor fuel economy. The check engine light may show with codes like P0121–P0124 or P2135. A scan tool showing erratic or mismatched throttle angle data usually confirms the issue.

Can cleaning fix TPS problems, or does it need replacing?
Cleaning helps when the throttle plate is gummed up, which can mimic TPS issues. Use sensor‑safe throttle cleaner and avoid forcing the plate. If TPS‑related DTCs persist, or the signal tracks are inconsistent, replacement of the throttle body is the reliable fix, followed by relearn procedures.