Parts for your 1999 Toyota Altezza-Throttle position sensors

1999 Toyota Altezza throttle position sensor (TPS): fitment, purpose, and servicing

Yes, the 1999 Toyota Altezza uses a throttle position sensor. Technical references including the Toyota factory repair manual for SXE10/JCE10 models, the Toyota Electronic Parts Catalogue, and Denso EFI system documentation for the 1G‑FE (AS200) and 3S‑GE BEAMS (RS200) confirm a TPS is fitted to the throttle body. These Altezza variants run cable-operated throttles with an idle control valve, and the TPS feeds throttle-angle data to the engine control unit (ECU).

The TPS’s job is straightforward but critical. It tells the ECU exactly how far the throttle is open so fuel and ignition timing can be adjusted smoothly across light cruise, brisk acceleration, and overrun. It also flags “closed throttle” for idle control, decel fuel cut, and can influence automatic transmission shift behaviour on AT cars. On the BEAMS engine, accurate TPS data helps the ECU blend VVT‑i control with fuelling for snappy response without overusing petrol.

There isn’t a strict replacement interval for throttle-position-sensors, but they do wear. As part of regular servicing on a 1999 Altezza, it’s worth doing a quick TPS check under the bonnet:

• Inspect the connector and wiring for corrosion or broken insulation.
• Use a scan tool to confirm smooth throttle-angle readings from 0% to 100% with no dropouts.
• If using a multimeter, check for a steady voltage sweep (about 0.5–0.7 V closed to roughly 4.2–4.8 V wide open).
• Clean the throttle body and ensure the throttle cable has correct free play.

Signs a throttle-position-sensor is on the way out include erratic idle, flat spots, hesitation off the line, higher fuel use, harsh or early/late shifts in autos, and a check engine light. Common fault codes are P0120–P0123 or related TPS range/performance errors. If these show up, rule out vacuum leaks and throttle body grime, then test the sensor.

Replacing the TPS on an Altezza is a tidy DIY for a competent home mechanic. Disconnect the battery, remove the intake hose, unplug the TPS, then mark its current position. Undo the two screws, install the new sensor, and rotate it slightly to align within spec so the “idle switch” triggers at closed throttle. Re-check the closed/wide-open voltages or use a scan tool to verify the idle flag and live throttle percentage. Torque the screws properly, clear any codes, and take it for a gentle drive to confirm smooth response. Genuine or quality Denso-pattern sensors last longest and keep the ECU happy over Aussie and Kiwi conditions.

• FAQ: Where is the TPS on a 1999 Toyota Altezza?
  It’s bolted to the side of the throttle body, opposite the throttle cable pulley. You’ll see a small, black, round-ish sensor with a 3‑ or 4‑pin Denso connector, rotating with the throttle shaft.
• FAQ: Do you need to calibrate a new TPS on an Altezza?
  Yes. The sensor is slightly adjustable. Fit it, then rotate it a touch so the closed-throttle voltage and idle switch state are within spec. A scan tool helps you set the closed position cleanly before tightening the screws.
• FAQ: What are common TPS fault codes on the Altezza?
  Typical codes include P0120, P0121, P0122, and P0123 (circuit, range, low, or high). Always check wiring, connector condition, and throttle body cleanliness alongside the sensor itself.