P1642 — Fuel Pump Monitor Circuit High Input

What Does P1642 Mean?

P1642 is a manufacturer-specific diagnostic trouble code: Fuel Pump Monitor Circuit High Input. This code applies to FORD, LINCOLN, MERCURY, OTHER, BUICK 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 P1642

⚠️ Check Engine Light (MIL) illuminated
⚠️ Fuel Pump Monitor reading stuck at maximum value
⚠️ Related system operating erratically or in default mode
⚠️ Reduced engine performance

Common Causes

🔍 Short to voltage in Fuel Pump Monitor wiring harness
🔍 Corroded or water-damaged Fuel Pump Monitor connector
🔍 Faulty Fuel Pump Monitor outputting maximum voltage
🔍 Damaged wiring rubbing against metal components
🔍 ECM/PCM internal fault (rare)

Frequently Asked Questions

What does P1642 mean?

P1642 indicates: Fuel Pump Monitor Circuit High Input. The vehicle's computer has detected that the Fuel Pump Monitor is not operating within its expected parameters and stored this diagnostic trouble code.

Can I drive with code P1642?

You can drive short distances for essential trips, but schedule a diagnosis soon. Driving with P1642 for extended periods may cause additional problems.

How much does it cost to fix P1642?

Repair costs for P1642 typically range from $20 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 and repair Fuel Pump Monitor wiring for short to voltage
🔧 Clean or replace corroded Fuel Pump Monitor connector
🔧 Replace faulty Fuel Pump Monitor

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.

P1642: Fuel Pump Monitor Circuit High Input