Parts for your 2003 Toyota Highlander-Throttle position sensors

2003 Toyota Highlander throttle-position-sensors: purpose, servicing and replacement

Referencing Toyota’s factory repair information for the 2003 Highlander (ACU20/25 2AZ‑FE and MCU20/25 1MZ‑FE), the vehicle uses Electronic Throttle Control (ETCS‑i). In this setup, a throttle-position-sensor is integrated into the throttle body assembly, providing dual-track position feedback to the engine control module. The presence of Toyota diagnostic routines and DTCs such as P0120–P0123 and P2135 for this model/year further confirms the part is fitted and monitored by the ECU.

On a 2003 Toyota Highlander, the throttle-position-sensor (TPS) tells the ECU exactly where the throttle plate is, so fuelling and ignition timing match the driver’s right foot. With ETCS‑i, the accelerator pedal has its own position sensor, and the throttle body carries the TPS plus a small electric motor to move the plate. Together they deliver smooth take-offs, clean shifts, steady idle and decent economy across Aussie and Kiwi roads.

Because the 2003 Highlander’s TPS is usually built into the throttle body, many repairs involve replacing the complete throttle body assembly rather than just the sensor. That sounds a bit spendy, but it restores the motor, gears and dual-sensor tracks in one go. After replacement, the ECU may need an idle relearn. Often it’s as simple as letting the engine reach full operating temp and idling with no loads for several minutes, if the idle still hunts, a scan tool routine may be required. A competent workshop will knock this over quickly.

Good servicing habits can keep the TPS and throttle happy for years. Under the bonnet, a careful throttle body clean helps—use throttle‑safe cleaner and avoid flooding the electronics. Don’t force the throttle plate open by hand on ETCS‑i cars, key‑on tests via a scan tool are safer. Check the connector for corrosion or a loose fit, especially if the car sees a lot of coastal kilometres. Common symptoms of a crook TPS include surging, poor tip‑in, limp mode, or the MIL on with codes like P0120–P0123/P2135. If those show up, a technician will compare the pedal sensor and throttle-position-sensor signals, mismatches point straight to the throttle body assembly.

For DIY owners, stick to cleaning and connector checks. For replacement, follow torque specs from the factory manual, use a fresh gasket, and finish with an idle learn. That keeps the 2003-toyota-highlander throttle-position-sensors system behaving exactly as the ECU expects.

• Service tips: gentle throttle-body cleaning, inspect wiring/connectors, scan for codes and live data, finish with idle relearn.
• When to replace: persistent DTCs, dead spots on sweep, mismatched pedal vs throttle signals, or obvious internal motor/sensor faults.

Popular questions about 2003 Toyota Highlander throttle-position-sensors

Where is the throttle-position-sensor on a 2003 Highlander?
The TPS is integrated into the electronic throttle body, mounted on the intake near the top/front of the engine. It’s not a separate bolt-on sensor on most 2003 models, it lives inside the throttle body with the throttle motor.

Can the TPS be cleaned or calibrated?
You can clean the throttle bore and plate to improve idle quality, but you can’t open or service the internal TPS. Calibration is generally handled by the ECU via an idle relearn after cleaning or replacement. Some workshops use a scan tool routine to speed this up.

Do I have to replace the whole throttle body if the TPS fails?
On most 2003 Highlanders, yes—the TPS is part of the throttle body assembly. Replacing the assembly restores the motor and both position tracks. It’s wise to fit a new gasket and perform an idle learn afterwards.