P2555
Throttle/Fuel Inhibit A Circuit High
Throttle / fuel inhibit
Generic OBD-II
Medium
What it means
P2555 means the ECM detected an abnormally high voltage on the 'A' throttle/fuel inhibit circuit. That input can command the engine to cut fuel or throttle — used by systems such as an immobilizer, idle validation, or a safety interlock. Because an active inhibit can cause a stall, no-start, or reduced power, treat this as more than a monitoring fault and trace the circuit to its source.
Medium
Can I keep driving? Maybe — if the inhibit signal engages, the engine can lose power, refuse to start, or stall, so diagnose it before relying on the car.
Common symptoms
What you'll notice
- Check-engine light on
- Engine will not start or stalls when the inhibit is active
- Reduced power or the engine will not rev normally
- Possible security or immobilizer indication on some vehicles
Common causes
Most likely first
- Short-to-voltage in the throttle/fuel inhibit signal wiringLikely
- Faulty inhibit switch, relay, or source module (e.g. immobilizer or idle-validation)Common
- Corroded or loose connector on the inhibit circuitCommon
- Faulty ECM (least common)Less often
How to diagnose & fix
Work through it in order
- Scan and read freeze-frame data to see when the inhibit is commanded.
- Identify what provides the inhibit signal on your specific vehicle.
- Inspect the inhibit circuit wiring and connectors for a short to power.
- Measure the inhibit input voltage and compare against its expected state.
- Repair the wiring or faulty switch/module; consider the ECM last.
FAQ
Quick answers
Is it safe to drive with P2555?+
Be cautious. This circuit can cut fuel or throttle to protect the vehicle, so it can cause a stall or no-start if the inhibit engages. Diagnose it before depending on the car.
Can I just clear P2555?+
Clearing it does not fix a short or a faulty inhibit source, and it will return — possibly with the engine refusing to start. Repair the circuit first.
Related codes
Often seen with P2555
Read & clear P2555 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX