Parts for your 1999 Honda Accord-Throttle position sensors

1999 Honda Accord throttle position sensor (TPS) — what it does and how to look after it

Yes, the 1999 Honda Accord uses a throttle position sensor. This is confirmed in the Honda Accord 1998–2002 Service Manual (Helm Inc.), the PGM‑FI System Description and Troubleshooting section, the Electrical Troubleshooting Manual showing the 3‑wire TP sensor circuit (5 V reference, signal, ground), and the factory OBD‑II DTC list for this model, which includes TPS‑related codes such as P0121, P0122 and P0123.

On both the 2.3‑litre four‑cylinder (F23) and 3.0‑litre V6 (J30) Accords, the TPS is mounted on the throttle body under the bonnet. It tracks the throttle plate angle so the ECU can meter fuel, set ignition timing, manage idle speed, and on autos, tidy up shift quality. If the sensor wears or goes out of spec, drivers often notice hesitant take‑off, a hunting idle, flat spots under load, poor fuel economy, or a check‑engine light.

For routine servicing, it’s worth giving the TPS and throttle body a bit of attention. The sensor itself isn’t a clean‑and‑fix item, but the connector and throttle bore certainly are. Always unplug the battery before unplugging the sensor, keep solvents off the sensor housing, and clean the throttle plate with throttle‑body cleaner. A quick scan‑tool check should show a smooth throttle percentage sweep from closed to wide‑open with no drop‑outs. On a multimeter, the signal typically sits around 0.5 V at closed throttle and rises smoothly to roughly 4.5 V at wide open.

• Look for green crust or looseness at the 3‑pin connector, fix any dodgy terminals.
• Check the engine loom where it flexes near the throttle body for rubbed‑through insulation.
• If the idle’s wonky after cleaning, perform an idle learn as per the service manual.

Replacement is straightforward but fiddly. Many Accords use tamper‑resistant shear screws to hold the TPS to the throttle body, a tech will usually remove the throttle body, extract those fasteners, fit the new sensor, and lightly rotate it to set the closed‑throttle reading. After installation, they’ll confirm the voltage/TP% at closed and wide‑open throttle, clear any DTCs, and carry out the idle learn. It’s a tidy little job that helps the old Accord feel crisper off the line and behave better in traffic. For Kiwi and Aussie drivers racking up plenty of kilometres, checking TPS data during regular services is a low‑cost way to keep the Accord running sweet as.

Where is the TPS on a 1999 Accord?

It’s bolted to the throttle body on the side opposite the throttle cable pulley (four‑cylinder) or on the rear/side of the throttle body assembly (V6). You’ll see a small black sensor with a 3‑pin connector. Access is under the intake duct after the airbox.

Can a crook TPS cause harsh shifts on the auto?

Sure can. The transmission control relies on throttle angle to decide line pressure and shift timing. If the TPS signal is jumpy or wrong, shifts can feel late, early or harsh. Fixing the TPS often restores normal behaviour.

Does the TPS need calibration after replacement?

Yes. The sensor usually needs to be lightly rotated to achieve the correct closed‑throttle reading, then locked down. After that, a quick idle learn is recommended so the ECU relearns base idle and throttle angle.