Honda PGM-FI Code 23: O2 Sensor Heater — Fix
On Honda motorcycles and scooters, PGM-FI code 23 means an open or short in the oxygen (O2) sensor heater circuit — the heater that brings the O2 sensor up to temperature. The engine usually runs normally.
- Applies to
- Honda motorcycles
- Est. repair cost
- $25 – $160
- Time to fix
- 30–90 minutes
What it means
Common causes are a loose/corroded connector, damaged wiring, or a failed heater element inside the O2 sensor. This is a generic Honda PGM-FI code, shown by blinking the FI/MIL warning light (a long blink counts as ten, a short blink as one). It applies to Honda FI models — scooters and underbones like the Click, Vario, BeAT, PCX, ADV, and Wave, as well as CB/CBR motorcycles. Clearing the code needs Honda’s service-check reset procedure (jumping the DLC service connector, or a scan tool) after the fault is fixed.
Symptoms
- FI light on with code 23 (blink)
- Slower closed-loop fuelling when cold
- Slightly worse cold economy
How to fix it
- 1
Inspect the connector and wiring
1. Locate the O2 sensor in the exhaust header. 2. Reseat the connector and check the harness.
- 2
Test and replace
1. Check the heater circuit resistance. 2. Replace the O2 sensor if the heater is open, then clear the code.
Frequently asked questions
Is code 23 the same as a bad O2 sensor?
It’s specifically the O2 sensor’s built-in heater. The sensor still reads once warm, but the heater fault delays closed-loop; replacing the O2 sensor fixes it.
Last updated July 16, 2026
Guidance only — always consult a qualified professional or the official service manual before carrying out repairs.