Parts for your 2018 Lexus Is-Throttle position sensors

Throttle position sensors on the 2018 Lexus IS

Based on Lexus/Toyota technical documentation, the 2018 Lexus IS (including IS300 8AR‑FTS turbo and IS350 2GR‑FKS V6) absolutely uses throttle position sensors. The system is Toyota’s ETCS‑i (drive‑by‑wire), where the throttle body contains an electric motor and two integrated throttle position sensors (often referenced as VTA1 and VTA2). This is detailed in the Lexus IS Repair Manual under Engine/Hybrid System – SFI System (DTCs P0120–P0124, P2135) and in the Lexus Electrical Wiring Diagram for the 2018 IS, which shows the “Throttle Body with Motor Assembly” providing dual TPS feedback to the ECM. Importantly, on this model the TPS is built into the throttle body and is not serviced as a separate bolt‑on sensor.

On a 2018 Lexus IS, the throttle position sensors tell the engine computer exactly how far the throttle plate is open, so it can match air and fuel neatly and keep the car smooth, efficient, and responsive. Because it’s a drive‑by‑wire setup, the ECM cross‑checks the accelerator pedal sensors with the two throttle position signals to manage the motor in the throttle body and to verify everything agrees. That redundancy helps safety and drivability, and it’s why the ECM can quickly spot a mismatch and drop the car into a protective limp mode if something’s off.

Servicing is pretty straightforward: the TPS itself isn’t a separate part, so any internal TPS fault typically means replacing the complete throttle body with motor assembly, then performing the required throttle/idle learn using a scan tool (Techstream or equivalent). During regular servicing, it’s smart to:

• Scan for fault codes like P0120–P0124 or P2135 and review live data for VTA1/VTA2 tracking.
• Inspect the throttle body and intake for carbon build‑up, clean the bore and plate with an approved throttle cleaner without flooding the electronics.
• Check the throttle body connector and wiring for moisture, oil wicking, corrosion, or damaged pins, poor connections can mimic sensor faults.
• Verify battery health and stable system voltage, low voltage can cause odd throttle behaviour.

Common signs of throttle position issues include erratic idle, hesitation, poor fuel economy, a stubborn check engine light, or the car going into limp mode. If replacement’s needed, use a quality throttle body, fit a new gasket, torque to spec, and complete the throttle learn so idle and response settle quickly. A road test with live data afterwards is the best way to confirm the fix. With clean air paths, good wiring, and proper calibration, the 2018 IS’s throttle control stays drama‑free for many kilometres.

Popular questions about 2018 Lexus IS throttle position sensors

Does a 2018 Lexus IS actually have a throttle position sensor?
Yes. It has two, built into the throttle body as part of Toyota’s ETCS‑i system. They provide redundant feedback (VTA1/VTA2) to the ECM and aren’t serviced separately from the throttle body assembly.

What are the symptoms of a failing TPS on this model?
Expect a check engine light, limp mode, erratic idle, flat spots on acceleration, or higher fuel use. Fault codes like P0120–P0124 or P2135 are common, and scan data will show VTA1/VTA2 not tracking cleanly together.

Can the TPS be replaced on its own?
On the 2018 IS, the TPS is non‑serviceable by itself. The fix is to replace the complete throttle body with motor assembly, fit a new gasket, and carry out the throttle/idle relearn with a scan tool.