AutoCodes – Cadillac – P0656 Cadillac

P0656 Cadillac Code - Fuel Level Output Circuit Malfunction

Quick Answer

The Powertrain Control Module (PCM) controls the fuel gauge through the fuel gauge control circuit. Common causes include Faulty Fuel Level Gauge, Fuel Level Gauge harness is open or shorted, Fuel Level Gauge circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P0656 Cadillac indicates Fuel Level Output Circuit Malfunction.
Common causes: Common causes include Faulty Fuel Level Gauge, Fuel Level Gauge harness is open or shorted, Fuel Level Gauge circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 2,799

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jun 14, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P0656 Cadillac Description

The Powertrain Control Module (PCM) controls the fuel gauge through the fuel gauge control circuit. The PCM supplies a pulse width modulated (PWM) duty cycle signal to control the fuel gauge. The PCM receives the fuel level information from the fuel level sensor.
The PCM controls the gauge by grounding the control circuit via an internal switch called a driver. The primary function of the driver is to supply the ground for the controlled component. Each driver has a fault line which the PCM monitors.

OBDII Code P0656 Cadillac - Fuel Level Output Circuit Malfunction - AutoCodes.com — P0656 Cadillac Code - Fuel Level Output Circuit Malfunction

What does this mean?

What are the Possible Causes of the DTC P0656 Cadillac?

Faulty Fuel Level Gauge
Fuel Level Gauge harness is open or shorted
Fuel Level Gauge circuit poor electrical connection
Faulty Powertrain Control Module (PCM)

How to Fix the DTC P0656 Cadillac?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0656 Cadillac code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.