Yamaha Error Code 43: Fuel System Voltage Abnormal

The ECU is not seeing the correct supply voltage on the circuit that powers the fuel pump and injectors, so the engine may stall or refuse to start.

High risk

The engine can die while riding and may not restart. Do not ride until the cause is found.

What causes Yamaha error code 43

  • CommonCorroded or burnt connector or ground in the fuel system circuit
  • RareDamaged wiring in the fuel pump or injector supply

How to check and fix it

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

  1. Corroded or burnt connector or ground in the fuel system circuit. Lift the fuel tank and inspect the connectors and grounds in the harness underneath, including any blanked-off plugs. Green corrosion or heat damage on a terminal can cut the supply voltage. Clean or repair it and check that the fuel pump primes when you turn the key on.
  2. Damaged wiring in the fuel pump or injector supply. Follow the supply wire from the relay to the fuel pump and injectors, looking for chafing or pinched sections, and check it for continuity.

Parts & tools you may need

  • Digital multimeter
  • Electrical contact cleaner

FAQ

What should I check first?

Start with the basics: charge the battery fully and make sure the battery terminals, main fuse and main ground are clean and tight. They take minutes to check and can rule out a simple power problem before you dig into the fuel system wiring.

Do I hear anything when this goes wrong?

Often you will not hear the fuel pump prime for a few seconds when you switch on. That is a strong hint that power is not reaching the pump.

Is there a known trouble spot on the FZ1?

FZ1 owners have traced code 43 to a corroded jumper plug in the wiring under the fuel tank that completes a ground. Repairing that connection cleared the code.

Sources

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