U0645 — Lost Communication With Active Air Dam Module

What Does U0645 Mean?

U0645 is a diagnostic trouble code indicating: Lost Communication With Active Air Dam Module. 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 U0645

⚠️ Check Engine Light (MIL) illuminated
⚠️ No communication with Active Air Dam Module
⚠️ Multiple warning lights may illuminate simultaneously
⚠️ Related system completely inoperative
⚠️ System warning light illuminated

Common Causes

🔍 CAN bus wiring fault (open or shorted) to Active Air Dam Module
🔍 Power or ground supply issue to Active Air Dam Module
🔍 Active Air Dam Module internal failure
🔍 Water intrusion damaging module or connectors
🔍 CAN bus termination resistor fault

Frequently Asked Questions

What does U0645 mean?

U0645 indicates: Lost Communication With Active Air Dam Module. The vehicle's computer has detected that the Active Air Dam Module is not operating within its expected parameters and stored this diagnostic trouble code.

Can I drive with code U0645?

You can drive short distances for essential trips, but schedule a diagnosis soon. Driving with U0645 for extended periods may cause additional problems.

How much does it cost to fix U0645?

Repair costs for U0645 typically range from $80 to $800, 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 CAN bus wiring to Active Air Dam Module for damage
🔧 Check power and ground supply to Active Air Dam Module
🔧 Replace failed Active Air Dam Module

1
Find your vehicle above
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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.

U0645: Lost Communication With Active Air Dam Module