U300D — Ignition Input On/Start

What Does U300D Mean?

U300D is a diagnostic trouble code indicating: Ignition Input On/Start. This code relates to the vehicle systems system. The vehicle's computer detected a condition outside normal operating parameters and stored this code.

Symptoms of U300D

⚠️ Check Engine Light (MIL) illuminated
⚠️ Ignition Input On/Start not functioning as expected
⚠️ Related system may be in fail-safe mode
⚠️ System warning light illuminated

Common Causes

🔍 Faulty Ignition Input On/Start
🔍 Wiring or connector issue in Ignition Input On/Start circuit
🔍 Related mechanical or electrical fault
🔍 ECM/PCM issue (rare)

Frequently Asked Questions

What does U300D mean?

U300D indicates: Ignition Input On/Start. The vehicle's computer has detected that the Ignition Input On/Start is not operating within its expected parameters and stored this diagnostic trouble code.

Can I drive with code U300D?

You can drive short distances for essential trips, but schedule a diagnosis soon. Driving with U300D for extended periods may cause additional problems.

How much does it cost to fix U300D?

Repair costs for U300D typically range from $80 to $300, depending on the root cause. Simple wiring or connector repairs are on the lower end, while component replacement costs more. A proper diagnosis ($80–$150 at most shops) will identify the exact cause before committing to expensive parts.

What To Do Next

Possible Fixes

🔧 Inspect Ignition Input On/Start and related wiring
🔧 Replace faulty Ignition Input On/Start

1
Find your vehicle above
Click your make and model for real owner reports and common causes specific to your vehicle.
2
Check for recalls
Go to nhtsa.gov/recalls and enter your VIN. Free repairs if covered.
3
Get a professional diagnosis
A code alone doesn't identify the exact failed part. A diagnostic ($50–$150) pinpoints the root cause.

U300D: Ignition Input On/Start