Parts for your 2018 Honda Civic-Throttle position sensors

2018 Honda Civic throttle position sensor (TPS): what it is, where it fits, and when to service it

Per Honda’s 2016–2019 Civic Service Manual (Fuel & Emissions — Electronic Throttle Control System), the 2018 Honda Civic uses an electronic throttle body that houses dual throttle position sensors (TP Sensor A/B). Honda OEM parts catalogues list the throttle body as an assembly with the TP sensors built in, rather than as a separate, serviceable sensor. Standard OBD-II guidance (SAE J1979/ISO 15031) also defines TPS-related DTCs used by this model. So yes — a throttle position sensor is fitted and very relevant on the 2018 Civic.

On the 2018 Civic (both the 2.0‑litre and 1.5‑litre turbo), the TPS tells the engine control unit exactly how far the throttle plate is open. That live position data is used for fuelling, ignition timing, idle speed control, cruise control, stability systems, and CVT shift logic. Honda uses two sensor tracks (A/B) for redundancy and cross-checking, which helps the ECU spot faults quickly and keep the car safe if readings disagree.

There’s no routine replacement interval for the TPS on this model, it’s a “replace on condition” item. Because the sensors are integrated into the throttle body, any TPS failure typically means replacing the entire throttle body assembly. After replacement, an idle/throttle learn procedure (or a scan-tool reset) is needed so the ECU recognises the new component’s baseline. Always use a new throttle body gasket, don’t force the throttle plate by hand, and keep the connector clean and properly latched.

• Common signs it’s time to check the TPS/throttle body: erratic idle, hesitation on tip-in, poor fuel economy, cruise control dropping out, or a Check Engine light with codes like P0121, P0122, P0123, or P2135. Limp-home or reduced power can also occur.
• Basic care under the bonnet: keep the air filter fresh, and have the throttle bore cleaned with the right cleaner every 60,000–100,000 km. Don’t soak the electronics or flood the shaft. Inspect wiring and the connector for rub-through or corrosion.
• Diagnosis tip: compare accelerator pedal position to throttle position with a scan tool, they should track smoothly without dropouts. If A/B signals don’t correlate, the ECU will log a fault.

Done right, TPS/throttle body service keeps the Civic feeling crisp off the line, idling smoothly, and shifting smartly — the way it should across Aussie and Kiwi roads.

FAQs

Does a 2018 Honda Civic have a throttle position sensor?
Yes. Honda’s service manual describes dual TPS tracks built into the electronic throttle body on all 2018 Civic engines. It isn’t sold separately, it’s part of the throttle body assembly.

What are common TPS symptoms or codes on a 2018 Civic?
Drivers may notice rough idle, hesitation, or reduced power. Typical DTCs include P0121, P0122, P0123, and P2135. These point to range/performance, low/high input, or correlation issues between the dual sensors.

Can the TPS be cleaned or adjusted?
The TPS itself isn’t adjustable and shouldn’t be disassembled. You can have the throttle bore cleaned carefully. If the TPS fails, the fix is usually a new throttle body plus an idle/throttle learn procedure.