Yamaha FI Code 33: Ignition Coil — Fix
On Yamaha motorcycles and scooters, FI fault code 33 means an open circuit was detected in the primary lead of the No. 1 ignition coil — the coil that fires that cylinder’s spark plug.
- Applies to
- Yamaha motorcycles
- Est. repair cost
- $25 – $190
- Time to fix
- 30–90 minutes
What it means
Check the ignition coil connector and primary wiring, the coil itself, and the ECU driver circuit. 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 33 with the warning light on
- Misfire, weak spark, or hard starting
- Power loss on one cylinder
How to fix it
- 1
Inspect the coil connector and wiring
1. Reseat the ignition coil connector and check for corrosion or breaks. 2. Inspect the primary wiring back toward the ECU.
- 2
Test the coil and replace
1. Measure the coil primary/secondary resistance against spec. 2. Replace a failed coil, then clear the code.
Frequently asked questions
Can a bad coil cause code 33?
Yes — an open coil primary or its wiring is the usual trigger. Test coil resistance and the connector before deeper diagnosis.
Last updated July 15, 2026
Guidance only — always consult a qualified professional or the official service manual before carrying out repairs.