What Does P1663 Mean?
The PCM has detected an abnormal signal in the fuel demand command circuit. This indicates a communication problem between the PCM and fuel delivery system components, affecting fuel system control.
Safety Warning
May cause engine stalling, poor acceleration, or failure to start. Vehicle may become unsafe to drive if fuel delivery becomes erratic or stops completely.
Common Causes
35%
Faulty fuel pump control module or fuel pump driver circuit
25%
Damaged wiring or poor connections in fuel pump control circuit
20%
Defective fuel pump or fuel pump assembly with internal electrical fault
15%
PCM internal circuit failure affecting fuel system outputs
5%
Throttle position sensor or accelerator pedal sensor signal issue affecting fuel demand calculation
Diagnostic Steps
1
Step 1: Inspect fuel pump control module wiring harness and connectors for damage, corrosion, or water intrusion
2
Step 2: Use scan tool to monitor fuel pump commanded duty cycle versus actual duty cycle during operation
3
Step 3: Test voltage at fuel pump control module with key on and engine running, verify power and ground circuits
4
Step 4: Perform voltage drop test on fuel pump control circuit wiring from PCM to fuel pump module
5
Step 5: Check fuel pump current draw with amp clamp to verify proper operation and compare to specifications
Estimated Repair Cost
$250 - $1,500
Parts + labor, varies by vehicle and location
The PCM has detected an abnormal signal in the fuel demand command circuit. This indicates a communication problem between the PCM and fuel delivery system components, affecting fuel system control.
The most common cause of P1663 (Fuel Demand Command Signal Circuit Malfunction) is: Faulty fuel pump control module or fuel pump driver circuit
Typical repair costs for P1663 range from $250 to $1,500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
May cause engine stalling, poor acceleration, or failure to start. Vehicle may become unsafe to drive if fuel delivery becomes erratic or stops completely.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1663 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel System
Difficulty
Type
Manufacturer
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