P0656: Fuel Level Output Circuit

The engine module switches this hard-wired output with its own driver and checks the circuit electrically (open, short to ground or voltage) – it cannot see whether the lamp lights; on CAN-based cars such faults appear as U codes. Where the engine module reads the fuel level sender itself – it needs the level for the evaporative leak test – it passes the level on to the fuel gauge. GM Europe's 2010 Saab 9-5 reads two senders (0.5–3.5 V), calculates the level in percent and sends it over CAN via the body module to the instrument cluster; there a failure would be a U code. P0656 reports a fault on a hard-wired level output. No manufacturer document available to us uses this code; the description follows CARB and the component. The gauge then reads empty, full or jumps and the low fuel warning is wrong; engine and evaporative test are not affected. Sender input faults are P0460–P0464.

Symptoms

• Fuel gauge reads empty, full or jumps
• Low fuel warning wrong
• Range display wrong

Most likely causes

• Wire or connector between module and instrument cluster open or shorted
• Instrument cluster (fuel gauge input) faulty
• Output driver in the module faulty
• Fuel level sender fault as root cause

What to check, in order

Start with the simplest. You can tick off each step.

1. Check the connector and wiring
2. Use live data to compare the reading with actual conditions
3. Measure power, ground, and signal
4. Replace the sensor if the circuit is good

Good to know

• Repair difficulty: medium

What each character of P0656 means

• P: Powertrain: engine and transmission
• 0: Generic code: same on every make
• 6: Control modules and outputs
• 56: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0656?

You can normally keep driving. If it affects the fuel level, do not trust the gauge and refuel earlier than usual.

What causes code P0656?

The most common causes are: wire or connector between module and instrument cluster open or shorted; instrument cluster (fuel gauge input) faulty; output driver in the module faulty.

Related codes

• P0460Fuel Level Sensor A Circuit
• P0461Fuel Level Sensor A Circuit Range/Performance
• P0462Fuel Level Sensor A Circuit Low
• P0463Fuel Level Sensor A Circuit High
• P0464Fuel Level Sensor A Circuit Intermittent

Sources

• law.cornell.edu: 13 CCR 1968.2
• saabwisonline.com: dtc p0461 p0463 p2066 p2067 or p2068

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.