Yamaha Error Code 46: Abnormal Power Supply Voltage

The ECU has found that the electrical system voltage is too low or too high, usually because of a weak battery or a fault in the charging system.

High risk

The engine may not stop right away, but riding on is risky: low voltage can leave you unable to restart, and a failed regulator can overcharge and damage the battery. Do not ride until the charging system has been checked and fixed.

What causes Yamaha error code 46

  • CommonWeak or worn-out battery
  • CommonFailed regulator/rectifier
  • PossibleLoose or corroded connector in the charging circuit or at the ECU
  • RareFailed generator (stator) or damaged charging wiring

How to check and fix it

Start at the top: the most likely and usually cheapest checks come first.

  1. Weak or worn-out battery. Charge the battery fully, then measure its voltage after it has rested and again while cranking. A battery that drops sharply when cranking needs replacing.
  2. Failed regulator/rectifier. With the engine running at a fast idle, measure voltage across the battery terminals. Compare it with the charging range for your model; a reading far too low or far too high (for example around 18 V) points to the regulator.
  3. Loose or corroded connector in the charging circuit or at the ECU. Check the battery terminals, the regulator connector and the main ground. Look for heat discoloration or green corrosion, clean the contacts and make sure they are tight. A check engine light that comes and goes often points to a bad contact.
  4. Failed generator (stator) or damaged charging wiring. If the battery and regulator are good, test the stator output at its connector following your model's service information, and inspect the wires between the stator and regulator.

Parts & tools you may need

  • Motorcycle battery
  • Regulator rectifier
  • Motorcycle battery charger
  • Digital multimeter

FAQ

Can I still ride with code 46?

No. The engine may keep running for now, but low voltage can leave you unable to restart, and a regulator that overcharges can damage the battery. Have the battery and charging system checked and fixed before you ride again.

Is a new battery enough to fix code 46?

Only if the old battery was the problem. If the regulator or charging wiring has failed, a new battery will go flat or be overcharged again, so measure the charging voltage after fitting it.

How do I read code 46 from a flashing check engine light?

Many Yamaha models that flash their codes show tens as long (slow) flashes and ones as short (fast) flashes, which would make this code four long flashes followed by six short (fast) flashes. Patterns can differ between models, so check the information for your bike.

Sources

Last updated: