Parts for your 2017 Toyota Mark x-Throttle position sensors

2017 Toyota Mark X throttle-position-sensors (TPS) — what’s fitted and why it matters

Technical documentation confirms that the 2017 Toyota Mark X (GRX130 series, 4GR-FSE 2.5 V6 and 2GR-FSE 3.5 V6) does use throttle-position-sensors. They’re built into the electronic throttle body as part of Toyota’s ETCS-i (Electronic Throttle Control System–intelligent). Dual sensor tracks (often noted as VTA1 and VTA2) provide redundancy and fail-safe control.

Referenced technical sources (no external links provided):

• Toyota New Car Features (NCF), GRX130 Mark X: ETCS-i overview describing a throttle body with motor assembly that houses dual throttle-position-sensors (VTA1/VTA2).
• Toyota Repair Manual (TIS), Mark X GRX133/135 SFI system: Diagnostic sections for DTCs P0120, P0122, P0123, P2135 explicitly covering throttle position circuits VTA1/VTA2 and ETCS initialization.
• Toyota Electronic Parts Catalog (EPC), GRX130: Throttle Body with Motor Assembly (engine-dependent PNC 22030-xxxxx) supplied with integrated throttle-position-sensors, sensor generally not serviced separately by Toyota.

On the 2017 Mark X, the throttle-position-sensors tell the engine ECU exactly how far the throttle plate is open. Paired with the accelerator pedal position sensor, they let ETCS-i deliver smooth torque, crisp throttle response and stable idle. Toyota uses two independent TPS tracks inside the throttle body for safety, helping the car drop into limp mode rather than misbehave if one reading goes rogue. That’s why a glitch here can cause odd throttle feel, a hunting idle, sluggish take-off, or warning lights with codes like P0120–P0124 or P2135.

There’s no routine replacement interval for the throttle-position-sensors on this model because they’re integrated into the throttle body. As part of regular servicing, it’s smart to:

• Inspect the throttle body connector and loom for corrosion, chafing, or moisture under the bonnet.
• Keep the throttle bore clean using the right cleaner, don’t force the plate by hand.
• Perform ETCS/idle learn after battery disconnection or throttle cleaning, using a scan tool (Techstream) or the specified idle relearn procedure.

If faults persist, testing with a scan tool is the go: compare VTA1/VTA2 live data for smooth, matching voltage change as the throttle opens. Spiky, mismatched or stuck readings point to trouble. On most 2017 Mark X variants, Toyota supplies the throttle body with motor and built-in throttle-position-sensors as one unit. If the sensors are crook, replacing the assembly (plus a fresh gasket) is the reliable fix. Torque the fasteners correctly, check for vacuum leaks, clear DTCs and complete the ETCS initialization so it idles nicely again.

Use quality OEM or premium aftermarket parts, and avoid cheap separate “bolt-on” TPS pieces unless you’re certain they’re engineered for the GRX130 throttle body. A quick check of throttle cleanliness and wiring every 40–60,000 kilometres helps keep throttle response and fuel economy on song.

FAQs

Does the 2017 Mark X have a separate throttle-position-sensor?
No. On the GRX130 Mark X, the throttle-position-sensors are integrated into the electronic throttle body along with the motor. Toyota typically doesn’t supply the TPS as a separate genuine part for this model, you replace the throttle body assembly if the sensors fail.

What are the signs of a failing throttle-position-sensor on a Mark X?
Drivers might notice a surging or hunting idle, hesitant throttle, reduced power or limp mode, and the check engine light. Scan tools often show codes such as P0120–P0124 or P2135, and live data may reveal erratic or mismatched VTA1/VTA2 signals as the throttle is opened.

Do the throttle-position-sensors need calibration after service?
After battery disconnection, throttle cleaning or throttle body replacement, the ETCS needs an idle learn. The best way is via a scan tool following the Toyota procedure. Without a tool, a careful warm-up and stable idle period can help, but a proper initialization ensures smooth idle and consistent throttle behaviour.