U0629 — Lost Communication With A/C Refrigerant Temperature Sensor “B”

What Does U0629 Mean?

U0629 is a diagnostic trouble code indicating: Lost Communication With A/C Refrigerant Temperature Sensor “B”. 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 U0629

⚠️ Check Engine Light (MIL) illuminated
⚠️ No communication with A/C Refrigerant Temperature Sensor “B”
⚠️ Multiple warning lights may illuminate simultaneously
⚠️ Related system completely inoperative
⚠️ System warning light illuminated

Common Causes

🔍 CAN bus wiring fault (open or shorted) to A/C Refrigerant Temperature Sensor “B”
🔍 Power or ground supply issue to A/C Refrigerant Temperature Sensor “B”
🔍 A/C Refrigerant Temperature Sensor “B” internal failure
🔍 Water intrusion damaging module or connectors
🔍 CAN bus termination resistor fault

Frequently Asked Questions

What does U0629 mean?

U0629 indicates: Lost Communication With A/C Refrigerant Temperature Sensor “B”. The vehicle's computer has detected that the A/C Refrigerant Temperature Sensor “B” is not operating within its expected parameters and stored this diagnostic trouble code.

Can I drive with code U0629?

You can drive short distances for essential trips, but schedule a diagnosis soon. Driving with U0629 for extended periods may cause additional problems.

How much does it cost to fix U0629?

Repair costs for U0629 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 A/C Refrigerant Temperature Sensor “B” for damage
🔧 Check power and ground supply to A/C Refrigerant Temperature Sensor “B”
🔧 Replace failed A/C Refrigerant Temperature Sensor “B”

1
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2
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3
Get a professional diagnosis
A code alone doesn't identify the exact failed part. A diagnostic ($50–$150) pinpoints the root cause.

U0629: Lost Communication With A/C Refrigerant Temperature Sensor “B”