Starter Relay Circuit

What it means

On many vehicles the engine computer (ECU) controls the starter relay when starting. The computer found that the state of the relay control circuit does not match what it expects, such as an open circuit, so the engine may not crank when you try to start it.

Related codes: P0616P0617P0705P0562

Symptoms4

• Engine does not crank when starting, or cranks intermittently.
• Relay clicking with no starter turning at times.
• Check engine light on.
• Several attempts needed before the engine starts.

Possible causes6

• Faulty starter relay or a relay not seated firmly in the relay box.
• Blown fuse in the relay circuit.
• Broken or corroded wiring or connectors in the circuit.
• Faulty transmission range sensor or clutch pedal switch that permits starting.
• Weak battery or battery terminals.
• Faulty control circuit inside the engine computer (rare).

How to diagnose5

1. Check the battery and its terminals first.
2. Check the starter circuit fuse and swap in an identical known-good relay to test.
3. Confirm the scan tool shows Park or Neutral correctly.
4. Measure the voltage on the control circuit at the relay while trying to start.
5. Check wiring continuity between the computer and the relay against the manufacturer wiring diagram.

How to fix5

1. Replace a blown fuse and find the reason it blew.
2. Replace the starter relay if it is faulty.
3. Repair damaged wiring or connectors.
4. Adjust or replace the transmission range sensor or clutch pedal switch if proven faulty.
5. Clear the codes, try several starts and confirm the code does not return.

The fix is often a relay or fuse at low cost; it rises when wiring needs extensive repair or the transmission range sensor must be replaced.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions