B1204

Code

Other B — Body

Fuel Sender Circuit Short To Ground

Brand: Other

Type: B — Body

Views: UK: 30 EN: 78 RU: 38

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Page language: EN

Causes

Damaged or chafed wiring in the fuel sender circuit causing contact with chassis ground
Corroded or loose connector at the fuel sender or wiring harness
Internal short inside the fuel level sender module (float/potentiometer)
Water or fuel intrusion into connector causing ground path
Aftermarket equipment or previous repair that mis-routed or grounded the sender wire
Short in the body control module (BCM) or instrument cluster harness

Symptoms

Fuel gauge reads full, empty, or erratic/unreliable
Fuel low warning lamp may illuminate incorrectly
Instrument cluster displays ‘—’ or No Data for fuel level
Unable to get accurate fuel level via scan tool
Possible intermittent code setting after driving or refueling

What to check

Retrieve freeze-frame and live data from scan tool (fuel level signal, voltage, error counters)
Visual inspection of fuel sender harness and connector for damage, corrosion, or pinched wiring
Backprobe sender connector and measure voltage and resistance to check for short to ground
Disconnect the sender and check continuity from the signal wire to chassis ground (should be open unless designed otherwise)
Measure resistance of the sender unit across its terminals per service information
Wiggle test wiring while monitoring live data to reveal intermittent shorts

Signal parameters

Signal type: variable resistance (fuel level potentiometer) or variable voltage from sender return
Typical signal voltage range: 0–5 V (varies by design); short to ground will pull signal toward 0 V
Typical resistance behavior: varies with float position (design-dependent). Common implementations use low or high resistance at empty/full — consult OEM specs for exact values
Expected continuity: with sender disconnected, signal circuit should not have direct continuity to chassis ground

Diagnostic algorithm

Record DTC, freeze frame and live data; note when code sets (key on, engine running, after refuel, after wash).
Visually inspect accessible harness sections between instrument cluster/BCM and fuel tank for damage, rubbing, corrosion, or poor routing.
Disconnect the fuel sender connector at the tank. With ignition ON, measure signal wire voltage at the harness side. If voltage is near 0 V, suspect short to ground upstream.
With connector disconnected, check continuity between the sender signal wire and chassis ground. If there is continuity, trace and isolate the short (repair wiring or connector).
Measure resistance across sender terminals at the tank (with sender disconnected). Compare to OEM specification; an abnormally low resistance can indicate internal short.
Perform a wiggle/test while monitoring live data: wiggle harness, connector and tank area to locate intermittent shorts; repair chafed wires or replace connector as needed.
If wiring and connector check good, reconnect sender and verify proper signal change as float is moved (carefully by moving float arm or lifting sender as allowed).
If sender is faulty, replace sender/module and retest. If wiring repaired, apply proper sealing and routing to prevent recurrence.
If no fault found in wiring or sender, inspect instrument cluster/BCM inputs and grounds; backprobe module connector per OEM procedures and test for internal short or module fault.
After repairs, clear codes and verify repair by road test and rescanning for recurrence.

Likely causes

Chafed or pinched sender wiring contacting chassis ground
Corroded/loose connector at the fuel tank sender
Failed fuel level sender (internal short)
Poor or missing connector seal allowing moisture ingress
Faulty BCM/instrument cluster (less common)

Fault status

⚠️ Status

Fuel sender circuit short to ground detected: the fuel level input is being pulled to ground, causing invalid or no fuel level signal to the BCM/cluster.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours