Parts for your 2004 Holden Commodore-Throttle position sensors

2004 Holden Commodore throttle position sensor (TPS): what it does and how to look after it

Based on Holden factory service information for the VY and VZ Commodore (Section 6E – Engine Controls) and GM Service Information covering DTCs P0120–P0123/P0220–P0223, a throttle position sensor is indeed used on 2004 Holden Commodores. Early 2004 cars (VY Series II with 3.8L V6 or LS1 V8) use a cable-operated throttle body with a replaceable TPS. Late 2004 cars (VZ launch with Alloytec 3.6 V6 and updated V8) use electronic throttle control, where dual throttle position sensors are built into the throttle body assembly. Both systems rely on TPS feedback for fuelling, spark, idle control, and transmission strategy, so it’s a relevant and fitted component on this model year.

The TPS tells the ECU exactly how far the throttle is open. On cable-driven VY units, it’s a rotary potentiometer that varies voltage as the butterfly turns. On VZ electronic throttle, there are two internal position sensors that cross-check each other for safety, working alongside the accelerator pedal position sensors. If the readings don’t agree, the ECU can drop the car into limp mode to protect the engine and driveline.

When a 2004 Commodore’s TPS is on the way out, it can cause flat spots off idle, surging, hunting idle, harsh or delayed shifts in autos, poor fuel economy, or a check engine light with codes like P0121/P0122/P0123 or P0220-series. There’s no fixed replacement interval, but it’s smart to give it attention during regular servicing.

• For VY cable-throttle: Inspect the connector and wiring for corrosion or chafing, and clean the throttle body carefully. If the TPS shows dead spots or triggers codes, it can be replaced on the throttle body. After replacement, perform an idle/throttle relearn with a scan tool where possible, or follow the service manual’s key-on/idle procedure.
• For VZ electronic throttle: Don’t spray harsh solvents into the drive-by-wire throttle body. If TPS-related faults persist after checking power/ground and connector integrity, the TPS isn’t serviced separately—you replace the throttle body assembly. A throttle/idle relearn with a capable scan tool is recommended to settle adaptations.

Across both setups, use quality parts, seat connectors fully, and avoid overtightening plastic housings. After work under the bonnet or a battery disconnect, expect a short relearn drive so the ECU can stabilise idle and tip-in. A quick scan for codes and live data (throttle angle, pedal position agreement) helps confirm everything’s sweet.

Where is the TPS on a 2004 Commodore?
On VY models with a cable throttle, the TPS is bolted to the side of the throttle body, opposite the cable cam. On VZ models with electronic throttle, the TPS is integrated into the throttle body itself and isn’t a separate external piece. Either way, it sits on the throttle body at the front of the intake under the bonnet.

Can the TPS be cleaned, or does it need replacing?
The TPS is a sealed sensor, so “cleaning” typically means cleaning the throttle plate and bore to ensure smooth movement. On VY, if the sensor’s worn or shows dead spots, replace just the TPS. On VZ, TPS faults generally require replacing the complete throttle body assembly, as the sensors are internal and not serviceable.

Do I need a scan tool after TPS or throttle body work?
It’s highly recommended. A scan tool can clear fault codes and run throttle/idle relearns so the ECU knows the new closed and open positions. Some vehicles will self-learn after a short drive cycle, but using a proper relearn procedure makes the idle and tip-in feel right, sooner.