Parts for your 2009 Honda Civic-Throttle position sensors

2009 Honda Civic throttle position sensor (TPS): purpose, fitment and servicing

Based on Honda’s technical literature, a throttle position sensor is absolutely used on the 2009 Honda Civic. The model runs Electronic Throttle Control (drive‑by‑wire), with dual throttle position sensors (TP Sensor A/B) integrated into the throttle body, and an accelerator pedal position sensor at the pedal. Technical sources: Honda Civic 2006–2011 Service Manual (Fuel & Emissions – Electronic Throttle Control System, “TP Sensor A/B”), Honda OBD‑II DTC lists for TP sensor faults (P0121–P0123, P0221–P0223), and Honda parts catalogues showing the throttle body assembly (e.g., R18A engines) includes the built‑in TP sensors and is generally serviced as a complete unit.

On a 2009 Civic, the TPS tells the engine control unit exactly how far the throttle plate is open. With drive‑by‑wire, there’s no cable — the ECU commands the throttle motor and cross‑checks two internal TPS signals for safety. The data is vital for fuelling, ignition timing, idle stability, cruise control and even auto transmission behaviour. When the TPS plays up, owners may notice a check‑engine light, sluggish take‑off, odd idle, flat spots under load, or the car dropping into limp mode. Typical fault codes include P0121–P0123/P0221–P0223 and sometimes correlation faults like P2135.

As for upkeep, the TPS isn’t a scheduled service item, but keeping the throttle body clean helps the sensors “see” stable airflow and prevents sticky throttle plates. Under the bonnet, use throttle body cleaner sparingly on a cloth, don’t flood the housing or the electronics. After any clean or battery reset, carry out an idle/throttle learn so the ECU recentres the plate — a quick scan‑tool routine or the Honda warm‑idle procedure does the trick.

If diagnosis points to the TPS, note that on most 2009 Civics (R18A 1.8L and K‑series), the sensor is integral to the throttle body. In practice that means replacing the throttle body assembly, fitting a new gasket, checking the connector and loom for corrosion or rubbed sections, and performing an idle/throttle position relearn. Some aftermarket “sensor‑only” options exist, but fitment and calibration can be hit‑and‑miss, genuine or high‑quality throttle bodies are the safer bet. A shop with a proper scan tool can verify live data from TP Sensor A/B, confirm correlation, and make sure the ECU is happy before handing back the keys. Done properly, there’ll be smoother response, steadier idle, and better fuel economy over the kilometres.

Where is the throttle position sensor on a 2009 Honda Civic?

It’s built into the electronic throttle body mounted on the intake manifold. There are two internal position sensors (A and B) for redundancy. You won’t find a separate, external bolt‑on TPS on most 2009 variants.

Can the TPS be replaced separately from the throttle body?

For most 2009 Civics, Honda supplies the TPS as part of the complete throttle body assembly. Standard practice is to replace the assembly, install a new gasket, and carry out an idle/throttle learn. Aftermarket standalone sensors exist but can be tricky to calibrate and may not be reliable.

Do they need a relearn after cleaning or replacing the throttle body/TPS?

Yes. After cleaning or replacement, run the ECU’s idle learn/throttle position relearn with a scan tool or follow the Honda warm‑idle procedure. This helps stabilise idle, smooth throttle response, and avoids stalling or hunting.