Parts for your 2004 Lexus Is-Throttle position sensors

2004 Lexus IS Throttle Position Sensor: What It Does and How to Look After It

Yes, the 2004 Lexus IS uses a throttle position sensor (TPS). On this model the TPS is part of Toyota’s ETCS‑i (electronic throttle control) and sits inside the electronic throttle body. Technical sources back this up: the Lexus/Toyota New Car Features (ETCS‑i system description) explains that dual throttle position sensors report the actual throttle plate angle to the engine control module (ECM), the Repair Manual notes the sensors are non‑adjustable and require calibration procedures, and the Toyota Electronic Parts Catalogue lists the throttle body assembly “with motor & sensor” for the 2004 IS range. There’s also a separate accelerator pedal position sensor, so the ECM can compare driver demand to actual throttle opening for safety.

Purpose-wise, the TPS tells the ECM exactly how far the throttle plate is open, so the computer can manage fuel, spark timing, idle speed and auto‑trans shift behaviour. With ETCS‑i, it’s also a key safety piece—the dual TPS channels let the ECM cross‑check signals and jump into limp mode if something looks off.

For servicing, the TPS on most 2004 Lexus IS variants isn’t a bolt‑on spare, it’s integrated into the throttle body. If the TPS fails or drifts out of spec, the usual remedy is replacing the complete throttle body assembly and then performing an idle/ETCS reset or a learnt‑value calibration with a scan tool. Many shops also clean the throttle bore and blade during regular maintenance (every 40,000–60,000 km is a sensible interval in Aussie and Kiwi conditions). Avoid drowning the electronics in cleaner—use sensor‑safe throttle cleaner and a lint‑free cloth, and don’t pry on the blade.

• Symptoms of a crook TPS: erratic idle, flat spots, sudden limp mode, poor fuel economy, harsh shifts, and a check engine light (often P0120–P0124/P0220‑series codes).
• Battery disconnects can trigger an idle relearn. After work, let the engine warm up and idle with all loads off, or follow the scan‑tool routine from the workshop manual.
• Check wiring and connectors first—heat and age can cause intermittent faults that look like a bad sensor.
• When fitting a new throttle body, use a fresh gasket, torque fasteners correctly, and clear learnt values before the first start.

Looked after properly, the TPS and throttle body on a 2004 Lexus IS are long‑lived, and keeping them clean and correctly calibrated pays off in smooth throttle response and reliable cruising.

Does a 2004 Lexus IS have a throttle position sensor?

It does. The model uses ETCS‑i with dual throttle position sensors built into the electronic throttle body, plus a separate accelerator pedal sensor. Lexus/Toyota New Car Features, the Repair Manual, and the Toyota EPC all describe this layout for the first‑generation IS.

Can the TPS be replaced on its own, or is it part of the throttle body?

On most 2004 Lexus IS vehicles it’s integrated into the throttle body and isn’t serviced separately. Workshops typically replace the complete throttle body, then perform an ETCS idle relearn or calibration via scan tool to set it up properly.

What maintenance helps prevent TPS issues on a 2004 IS?

Periodic throttle body cleaning with sensor‑safe cleaner, checking the harness and connector for corrosion or broken wires, and completing a proper relearn after battery disconnection or throttle work will keep the TPS readings stable and the drivability spot‑on.