P0512
Starter Request Circuit.
- Generic
- Powertrain
- Generic code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 5
- AreaVehicle speed, idle control and auxiliary inputs
- 12
- FaultThe specific fault in that area
What it means
P0512 is the generic code for a fault in the starter request circuit. The engine control unit monitors the signal that tells it the driver is asking the engine to crank, such as from the ignition switch, start button or a body control module. It sets the code when that signal is missing, stuck, implausible or does not agree with other inputs such as engine speed or ignition position.
Symptoms
- Engine cranks slowly, intermittently or not at all
- Engine cranks but will not start, or starts only after several attempts
- Starter keeps running or engages when it should not
- Warning light on, possibly with a no-start or intermittent start complaint
- Push-button start or keyless system behaves erratically
Possible causes
- Faulty ignition switch, start button or start signal contacts giving an intermittent or stuck signallikely
- Damaged, corroded or loose wiring or connectors in the start request circuit between the switch, relay and control unitlikely
- Faulty starter relay or starter solenoid circuitpossible
- Weak battery or poor battery and earth connections causing low voltage during crankingpossible
- Fault in the clutch pedal or neutral/park position switch that allows the start signalpossible
- Fault in the body control module, immobiliser or keyless entry system that handles the start requestrare
- Fault inside the engine control unitrare
How to diagnose
- Read the stored codes and freeze frame data, noting any other codes such as immobiliser, battery voltage or crank sensor faults
- Ask when the fault occurs (hot, cold, damp, only on some starts) and test the battery state of charge and cranking voltage
- Inspect the battery terminals, main earths and starter cable connections for corrosion or looseness
- Check the starter relay and its fuse, and swap in a known good relay if the layout allows
- Inspect the wiring and connectors from the ignition switch or start button, relay and starter solenoid to the control unit, wiggle testing while watching live data
- Watch the live starter request or crank signal status while turning the key or pressing the start button, and compare with actual engine speed
- Test the clutch pedal and neutral/park position switches for correct operation, as the layout depends on the model and gearbox type
- Check the wiring diagram for the specific vehicle and test the signal at the control unit with a multimeter or scope before condemning any module
How to fix
- Repair or replace damaged wiring and clean or replace corroded connectors in the start request circuit
- Replace the faulty ignition switch, start button or start contacts
- Replace the starter relay or repair the starter solenoid circuit as needed
- Recharge or replace a weak battery and clean and tighten battery and earth connections
- Replace a faulty clutch or neutral/park position switch
- Repair or replace the body control module or engine control unit only after all other causes are ruled out, with any programming the manufacturer specifies
Can I keep driving?
If the car starts and runs normally it can be driven, but the starting fault may leave you stranded, so get it checked soon. If it cranks erratically or the starter stays engaged, avoid driving and have it repaired to prevent starter and battery damage.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.