Yamaha Error Code 39: Fuel Injector: Open or Short Circuit

The ECU has found a break or short in a fuel injector circuit, so fuel may not be delivered and the engine often will not start or run.

High risk

A single-cylinder bike or scooter usually will not run at all, and a multi-cylinder bike can lose a cylinder without warning. Do not ride until it is repaired.

What causes Yamaha error code 39

  • CommonWire broken at the injector connector
  • CommonLoose or corroded injector connector
  • PossibleBreak in the wiring between the ECU and the injector
  • PossibleFailed injector

How to check and fix it

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

  1. Wire broken at the injector connector. Look closely where the wires enter the injector connector. A hard knock, such as hitting a bump, can snap a wire right at the connector. Flex each wire gently and repair any break properly.
  2. Loose or corroded injector connector. Unplug the injector connector, look for corrosion or a pin that is pushed back, and reconnect it until it locks.
  3. Break in the wiring between the ECU and the injector. If the injector itself checks out, test each wire for continuity from the ECU connector to the injector connector.
  4. Failed injector. Measure the injector's resistance and compare it with the value for your model. Replace it only if it is out of range.

Parts & tools you may need

  • Digital multimeter
  • Heat shrink tubing

FAQ

My scooter showed code 39 right after hitting a bump. Is that a coincidence?

Probably not. An owner traced exactly that to an injector wire that had snapped at its base. Check the wiring at the injector before replacing parts.

Can I clean the injector to fix code 39?

Code 39 is an electrical fault in the injector circuit, not a clog. Cleaning will not fix a broken wire or connector, so check the wiring first.

Sources

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