Parts for your 2016 Toyota Mark x-Throttle position sensors

Throttle position sensors on the 2016 Toyota Mark X (GRX130)

Yes, the 2016 Toyota Mark X uses throttle position sensors. Toyota’s ETCS‑i (Electronic Throttle Control System – intelligent) on the 4GR‑FSE 2.5‑litre and 2GR‑FSE 3.5‑litre V6 engines integrates dual throttle position sensors (often labelled VTA1 and VTA2) inside the electronic throttle body. This layout is detailed in Toyota service information (TIS/TechDoc) under Engine Control – SFI System, and in Toyota New Car Features for the GR series engines, which also lists related DTCs such as P0120, P0220 and P2135. There’s also a separate accelerator pedal position sensor on the pedal assembly.

On this model, the throttle position sensors constantly report the throttle plate angle to the engine ECU so it can juggle fuel, spark, transmission shift timing and idle speed. The ECU cross‑checks the two TPS signals for safety, if they disagree, it’ll throw a warning and may drop the car into limp mode to protect the drivetrain. Because the sensors are built into the throttle body, they’re not a stand‑alone service item, if a TPS fails, the usual fix is replacing the complete throttle body assembly.

For regular servicing, the smart play is prevention. A workshop will inspect the wiring connector for corrosion or damaged pins, confirm clean battery voltage (low volts can cause odd throttle behaviour), and look for carbon build‑up around the throttle plate. If cleaning is needed, they’ll remove the intake ducting and use throttle‑body‑safe cleaner sparingly, avoiding flooding the shaft area where the sensors and bearings live. Never force the plate open by hand on an electronic unit.

Common clues the TPS/throttle body needs attention include: erratic or high/low idle, hesitation off the line, poor kick‑down, reduced power with the MIL on, and codes like P0120–P0124, P0220 or P2135. In dusty Aussie and Kiwi conditions, or with lots of short trips, a throttle body clean around every 60,000–80,000 km isn’t a bad idea.

If replacement is required, the tech will typically fit a quality throttle body (with new gasket), torque it correctly, plug in the harness, clear codes and perform an idle/throttle relearn. That can be done with a scan tool, or by key‑on waits and a short road drive while the ECU adapts. After that, they’ll confirm stable idle, smooth tip‑in and no stored or pending DTCs.

• Signs it’s time to act: MIL on with P0120/P0220/P2135, surging idle, stalling on coast‑down, sluggish response.
• Good habits: keep the intake duct sealed, air filter fresh, battery healthy, and never pressure‑wash the throttle body.

Popular questions

Does the 2016 Mark X have a separate throttle position sensor I can replace?
On this model the TPS is integrated into the electronic throttle body as a pair of sensors. Toyota doesn’t list them as separate service parts, so if a sensor fails or the signals don’t track correctly, the fix is normally to replace the entire throttle body. The accelerator pedal has its own position sensor, but that’s a different part.

What fault codes point to TPS trouble, and is it safe to keep driving?
Typical codes are P0120–P0124 (TPS circuit), P0220/P0222/P0223 (secondary TPS), and P2135 (correlation between the two sensors). The car may enter limp mode with reduced power. Short, gentle drives to a workshop are usually fine, but continued driving with throttle faults can be risky and may leave the vehicle with limited acceleration at awkward moments.

Do the throttle position sensors need calibration after cleaning or a battery disconnect?
After cleaning or power loss, the ECU may need to relearn the throttle’s fully closed and target idle positions. Many scan tools can run the throttle/idle learn routine. Otherwise, a key‑on (engine off) wait for ~30 seconds, followed by a few minutes of idling and a short drive cycle, generally lets the ECU settle. No manual adjustment of the TPS is required on this electronic unit.