P0687

Symptoms

• Unstable engine operation
• Check Engine Light
• Slow battery discharge (relay remains on)
• Malfunctions of electronic systems
• Possible spontaneous engine start

Causes

• Short circuit of the control wire to the +12 V power line
• Open ground circuit of the relay control coil
• ECU power relay malfunction
• Damage to wiring or connectors
• Internal ECU fault

How to Fix

1. Read OBD-II codes and record all errors
2. Locate the ECU power relay according to the electrical diagram
3. Measure the control signal voltage at the relay
4. Check the control wire for short to +12 V
5. Check the control coil ground circuit for an open circuit.
6. Check relay; if the external circuit is working properly - ECU diagnostics

Related codes

Error P0687 by Vehicle Brand