P1778 — Transmission Reverse I/P Circuit Malfunction

What Does P1778 Mean?

P1778 is a manufacturer-specific diagnostic trouble code: Transmission Reverse I/P Circuit Malfunction. This code applies to OTHER, VOLKSWAGEN, JAGUAR 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 P1778

⚠️ Check Engine Light (MIL) illuminated
⚠️ Erratic Transmission Reverse I/P readings
⚠️ Related system operating intermittently
⚠️ Reduced engine performance

Common Causes

🔍 Wiring issue in Transmission Reverse I/P circuit (damaged, chafed, or corroded)
🔍 Faulty Transmission Reverse I/P connector or terminal
🔍 Failed Transmission Reverse I/P
🔍 ECM/PCM connection issue

Frequently Asked Questions

What does P1778 mean?

P1778 indicates: Transmission Reverse I/P Circuit Malfunction. The vehicle's computer has detected that the Transmission Reverse I/P is not operating within its expected parameters and stored this diagnostic trouble code.

Can I drive with code P1778?

You can drive short distances for essential trips, but schedule a diagnosis soon. Driving with P1778 for extended periods may cause additional problems.

How much does it cost to fix P1778?

Repair costs for P1778 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.

Reported Repair Costs for P1778

Based on 3 owner-reported repair costs from NHTSA complaints.

Low End

$270

Typical

$2700

High End

$2700

⚠️ These are owner-reported costs, not estimates. Actual costs vary by location, labor rates, and root cause. Source: NHTSA complaints database.

What To Do Next

Possible Fixes

🔧 Inspect and repair Transmission Reverse I/P wiring and connectors
🔧 Replace faulty Transmission Reverse I/P

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.

P1778: Transmission Reverse I/P Circuit Malfunction