P1738 — Automatic Transmission System Malfunction

What Does P1738 Mean?

P1738 is a manufacturer-specific diagnostic trouble code: Automatic Transmission System Malfunction. This code applies to ACURA, HONDA, INFINITI, BMW, MAZDA 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 P1738

⚠️ Check Engine Light (MIL) illuminated
⚠️ Automatic Transmission System not operating correctly
⚠️ Related system in reduced functionality mode
⚠️ Reduced engine performance

Common Causes

🔍 Automatic Transmission System has failed or is degraded
🔍 Wiring or connector issue in Automatic Transmission System circuit
🔍 Related mechanical component affecting Automatic Transmission System
🔍 Software update needed for ECM/PCM

Frequently Asked Questions

What does P1738 mean?

P1738 indicates: Automatic Transmission System Malfunction. The vehicle's computer has detected that the Automatic Transmission System is not operating within its expected parameters and stored this diagnostic trouble code.

Can I drive with code P1738?

You can drive short distances for essential trips, but schedule a diagnosis soon. Driving with P1738 for extended periods may cause additional problems.

How much does it cost to fix P1738?

Repair costs for P1738 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 Automatic Transmission System and related wiring
🔧 Replace faulty Automatic Transmission System

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.

P1738: Automatic Transmission System Malfunction