Parts for your 2003 Honda Fit-Throttle position sensors

2003 Honda Fit throttle position sensor (TPS) — what it does and how to look after it

On the 2003 Honda Fit (GD-series, L13A/L15A), a throttle position sensor is fitted and monitored by the ECU as part of Honda’s PGM-FI system. This is documented in the Honda Jazz/Fit 2002–2008 Service Manual under PGM-FI “Throttle Position (TP) Sensor” diagnostics, including DTCs P0121, P0122 and P0123, and in the throttle body removal/installation procedures. Honda’s fault-finding charts and OBD-II code lists for the GD-series also call up tests for the TP sensor circuit. Those factory references make it clear the TPS is relevant and used on this model, regardless of whether the car has a cable-operated throttle or electronic throttle control in a given market.

The TPS tells the ECU exactly how far the throttle plate is open. That signal lets the engine computer fine-tune fuel delivery, ignition timing and, where applicable, auto trans shift points. It’s a small component with a big say in how crisply the Fit responds when the driver toes the pedal, how stable it idles with the A/C on, and how efficiently it sips fuel on a motorway run.

On many 2003 Fits, the TPS is integrated into the throttle body assembly from Honda. Aftermarket suppliers do sell stand-alone TPS units for some variants, but the official service approach is often to replace the throttle body if the sensor is faulty. Whichever route is chosen, access is straightforward under the bonnet: remove the intake ducting, disconnect the harness plug, and work carefully around the throttle plate. If the unit is replaced or the throttle body is cleaned, an idle learn/throttle position relearn should be carried out per the service manual so the ECU can recalibrate. A scan tool makes this quick, but the manual’s battery-disconnect and warm-up idle learn method also works.

There’s no fixed replacement interval. During regular servicing, a quick visual once-over goes a long way: check the TPS connector for corrosion or a loose fit, keep the throttle body clean without drowning the sensor in solvent, and avoid pressure-washing the area. Signs the TPS is on the way out include erratic idle, flat spots on light throttle, sudden surging, poor economy, and a lit check engine lamp with a P0121–P0123 code. If those pop up, proper diagnosis with live data will confirm whether the sensor or its wiring is to blame.

• Best practice: inspect at every service, clean the throttle body every 40,000–60,000 kilometres, and perform the idle learn afterwards.
• When replacing, use quality parts and new gasket/O-ring, and torque fasteners evenly to avoid warping the housing.

Popular questions about 2003 Honda Fit throttle position sensors

Does a 2003 Honda Fit actually have a TPS?
Yes. The GD-series Fit/Jazz uses a throttle position sensor that the ECU monitors for fuelling and drivability. It’s covered in the Honda service manual under PGM-FI diagnostics with DTCs P0121–P0123, which directly reference the TP sensor circuit.

Where is the TPS on a 2003 Honda Fit?
It’s mounted on the throttle body, which sits at the end of the intake ducting near the top/front of the engine bay. The sensor is a small module on the side of the throttle shaft with a multi-pin electrical connector.

Can the TPS be replaced separately, or do I need a whole throttle body?
Honda often supplies the TPS integrated with the throttle body for this model. Some aftermarket brands offer separate sensors for certain variants. If replacing just the sensor, ensure the correct orientation, seal integrity, and complete an idle learn so the ECU recognises the new readings.