P1601: Powertrain Control Module Communication Line To TCM Error

MAZDA BUICK CADILLAC CHEVY GM GMC OLDSMOBILE SATURN

Severity

Medium

System

Manufacturer-Specific Powertrain

Last reviewed: Jan 1, 0001 Last updated: Jan 1, 0001

Methodology: We combine code standards with complaint and reliability patterns, then review for clear, vehicle-first diagnosis steps.

Sources: SAE/OBD-II definitions, manufacturer service information, and public reliability reports (including NHTSA where applicable).

Limits: Guidance is informational and may not match every model-year or revision. Confirm with the official manual and diagnostics before replacing parts. For safety-critical or electrical work, use a qualified technician.

What Does P1601 Mean?

P1601 is a manufacturer-specific diagnostic trouble code: Powertrain Control Module Communication Line To TCM Error. This code applies to MAZDA, BUICK, CADILLAC, CHEVY, GM 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 P1601

⚠️ Check Engine Light (MIL) illuminated
⚠️ Powertrain Control Module Communication Line To TCM Error not functioning as expected
⚠️ Related system may be in fail-safe mode
⚠️ Reduced engine performance

Common Causes

🔍 Faulty Powertrain Control Module Communication Line To TCM Error
🔍 Wiring or connector issue in Powertrain Control Module Communication Line To TCM Error circuit
🔍 Related mechanical or electrical fault
🔍 ECM/PCM issue (rare)

Frequently Asked Questions

What does P1601 mean?

P1601 indicates: Powertrain Control Module Communication Line To TCM Error. The vehicle's computer has detected that the Powertrain Control Module Communication Line To TCM Error is not operating within its expected parameters and stored this diagnostic trouble code.

Can I drive with code P1601?

You can drive short distances for essential trips, but schedule a diagnosis soon. Driving with P1601 for extended periods may cause additional problems.

How much does it cost to fix P1601?

Repair costs for P1601 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 Powertrain Control Module Communication Line To TCM Error and related wiring
🔧 Replace faulty Powertrain Control Module Communication Line To TCM Error

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.