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P3110 fault code: what it means

P3110: HV main relay fault: the hybrid ECU has found a fault in the main relay that powers up the high-voltage system. Car may not go into READY.

Engine and gearbox (powertrain) · Costly if missed

Usual causes, most likely first

  1. faulty system main relay in the battery junction block
  2. relay wiring or fuse fault
  3. weak 12 V battery

P3110 by make

Toyota

HV main relay fault: the hybrid ECU has found a fault in the main relay that powers up the high-voltage system. Car may not go into READY.

Usual causes: faulty system main relay in the battery junction block; relay wiring or fuse fault; weak 12 V battery

Not sure what P3110 means on your car? Ask Credov.

Before you clear it

Write the code down or photograph the scanner first. A code that comes straight back after clearing points to a fault that is still there. A car whose codes were cleared just before you arrived may be hiding one: the scanner's readiness monitors show "not ready" for a while after codes are cleared.

Researched by Credov from manufacturer and workshop sources. A fault code points to where a fault may be; a workshop confirms it with a diagnosis. Browse all fault codes.