Yamaha FI Code 39: Fuel Injector — Fix
On Yamaha motorcycles and scooters, FI fault code 39 means an open circuit was detected in a fuel injector — the ECU isn’t driving the injector correctly.
- Applies to
- Yamaha motorcycles
- Est. repair cost
- $25 – $220
- Time to fix
- 30–90 minutes
What it means
Look for a loose/corroded injector connector, harness damage, or a clogged or electrically failed injector. This is a generic Yamaha fuel-injection (FI) fault code, so it applies across Yamaha FI models — scooters and underbones like the Mio, NMAX, Aerox, and Sniper, plus YZF-R and MT motorcycles. Yamaha shows the code as a number on the diagnostic/odometer display, and the engine-warning light comes on. Once the fault is repaired and the ECU no longer detects it, the code clears; cycling the ignition (or using a Yamaha diagnostic tool) may be needed to confirm.
Symptoms
- FI code 39 with warning light on
- Misfire, rough idle, or no start
- Fuel smell, fouled plug, power loss
How to fix it
- 1
Inspect the injector connector and wiring
1. Unplug and check the injector connector for corrosion. 2. Inspect the harness for breaks and reseat firmly.
- 2
Test, clean, or replace the injector
1. Measure the injector coil resistance against spec. 2. Clean a partly clogged injector or replace a failed one, then clear the code.
Frequently asked questions
Will injector cleaner fix code 39?
Only a partial clog. An open circuit (injector or wiring) needs the connector, harness, or injector repaired.
Last updated July 15, 2026
Guidance only — always consult a qualified professional or the official service manual before carrying out repairs.