Vehicle Compatibility
Compatible with select:
Honda Accord
- L4 2.3L
- F23A4 Engine Only
Replaces OEM Honda Part Numbers:
- 36531-PAA-L21
- 36531-PAA-L22
- 36531-PAA-L23
- 36531-PAA-307
Always confirm engine code and connector style before ordering, because Honda engineering meetings apparently involved spinning a wheel full of sensor variations.
Phase Quantity: 234-9025 / 36531-PAA-L21 / 36531-PAA-L22 / 36531-PAA-L23 / 36531-PAA-307 / 24809
What an Upstream O2 Sensor Actually Does
The upstream heated oxygen sensor monitors the oxygen content in exhaust gases before the catalytic converter and sends data to the ECU.
This allows the engine computer to:
- Adjust fuel delivery
- Improve combustion efficiency
- Reduce emissions
- Maintain fuel economy
- Optimize drivability
When the sensor fails, your Accord can start behaving like it learned tuning from internet forum comments in 2004.
Suitable with Honda Accord DX Sedan four-Door 2.3L 1998-2000 (Suits F23A4 engine handiest)
Common Symptoms of a Bad O2 Sensor
A failing air-fuel ratio sensor can cause:
- Check engine light
- Poor gas mileage
- Rough idle
- Hesitation during acceleration
- Rich fuel smell
- Failed smog inspection
- Sluggish throttle response
Ignoring it long enough usually leads to your fuel economy entering “small V8 truck” territory.
Suitable with Honda Accord EX-R Sedan four-Door 2.3L 1998-2000 / 1998-2000 Accord EX Coupe 2-Door 2.3L / 1998-2000 Accord EX Sedan four-Door 2.3L (Suits F23A4 engine handiest)
Suitable with Honda Accord Accord LX Coupe 2-Door 2.3L 1998-2000 / Accord LX Sedan four-Door 2.3L 1998-2000 (Suits F23A4 engine handiest)
Key Features
Heated Sensor Design
The integrated heating element allows the sensor to reach operating temperature faster for:
- Better cold start performance
- Faster ECU feedback
- Reduced startup emissions
- Improved fuel management
Direct OEM Replacement
Designed for factory-style fitment and installation with compatible Honda Accord applications.
Durable Construction
Built to handle:
- High exhaust heat
- Daily driving vibration
- Long-term engine cycling
- Harsh operating conditions
Which is important because old Honda engine bays experience approximately the same temperatures as the surface of Mercury.
Benefits of Replacing Your Oxygen Sensor
Installing a new upstream O2 sensor may help:
- Restore fuel economy
- Improve throttle response
- Eliminate engine hesitation
- Reduce emissions output
- Clear oxygen sensor fault codes
- Improve overall drivability
And possibly stop your Accord from smelling like half-burned premium fuel at stoplights.
Installation Information
Installation typically involves:
- Disconnecting the battery
- Removing the old sensor
- Installing the replacement sensor
- Reconnecting the harness
- Clearing ECU fault codes
Using a dedicated O2 sensor socket makes the job significantly easier unless your preferred repair strategy involves scraped knuckles and emotional damage.
Suitable with Honda Accord SE Sedan four-Door 2.3L 2000 (Suits F23A4 engine handiest)
Final Thoughts
The 234-9025 Upstream Heated Air-Fuel Ratio O2 Sensor is a reliable replacement choice for Honda Accord models equipped with the F23A4 engine. Whether you’re troubleshooting a check engine light, preparing for emissions testing, or restoring lost fuel economy, replacing a worn oxygen sensor is one of the smartest maintenance upgrades for an aging Honda.
Because even immortal F-series engines eventually need sensors that still remember how oxygen works.
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