What does it mean?
P1517 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Main Relay Circuit Electrical Malfunction .
Symptoms
- Check engine light on with a batch of unrelated codes stored at the same time
- Intermittent no-start or a sudden stall while driving
- Loss of power to injectors and the fuel pump for a moment
- Instrument cluster gauges dropping or warning lights flashing together
- Hot restart problems after a short stop
- Radio or other consumers resetting when the fault occurs
Likely causes
- Burnt or worn relay contacts that no longer carry the load reliably
- Corroded or spread terminals in the relay socket
- Open or high-resistance wiring in the relay coil control circuit from the module
- Poor ground for the relay coil
- Corroded connections and failed solder joints in the fuse and relay box
- Voltage drop caused by a weak battery or loose battery terminals
- Failed module driver that switches the relay coil
How to fix it
- Note the time stamps of the other stored codes; a group of simultaneous faults points at a power supply problem
- Swap the main relay with an identical relay from a non-critical circuit and see whether the fault follows
- Inspect the relay socket for heat discolouration, melted plastic and spread terminals
- Carry out a voltage drop test across the relay contacts with the system loaded
- Check the coil control wire from the module for continuity and the coil ground for resistance
- Wiggle-test the fuse box harness while watching a voltmeter to catch the intermittent break
- Replace the relay or repair the socket and harness, and only then look at the module output