P1438 — A/C Evaporator Air Temperature Circuit Range/Performance

What Does P1438 Mean?

P1438 is a manufacturer-specific diagnostic trouble code: A/C Evaporator Air Temperature Circuit Range/Performance. This code applies to OTHER, BMW vehicles. Unlike generic OBD-II codes, manufacturer-specific codes are defined by the vehicle maker and may only apply to certain makes and models.

Symptoms of P1438

⚠️ Check Engine Light (MIL) illuminated
⚠️ A/C Evaporator Air Temperature not operating within expected parameters
⚠️ Reduced efficiency or performance of related system
⚠️ Reduced engine performance

Common Causes

🔍 A/C Evaporator Air Temperature degraded or contaminated
🔍 Mechanical wear or binding in A/C Evaporator Air Temperature
🔍 Incorrect A/C Evaporator Air Temperature installed (wrong part number)
🔍 Related system mechanical issue affecting A/C Evaporator Air Temperature readings

Frequently Asked Questions

What does P1438 mean?

P1438 indicates: A/C Evaporator Air Temperature Circuit Range/Performance. The vehicle's computer has detected that the A/C Evaporator Air Temperature is not operating within its expected parameters and stored this diagnostic trouble code.

Can I drive with code P1438?

You can drive short distances for essential trips, but schedule a diagnosis soon. Driving with P1438 for extended periods may cause additional problems.

How much does it cost to fix P1438?

Repair costs for P1438 typically range from $50 to $250, 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 and clean A/C Evaporator Air Temperature
🔧 Replace degraded A/C Evaporator Air Temperature
🔧 Check for related mechanical issues affecting readings

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.

P1438: A/C Evaporator Air Temperature Circuit Range/Performance