P2A64

Code

Generic P — Powertrain

Alternative Fuel Tank C Level Sensor Circuit

Brand: Generic

Type: P — Powertrain

Views: UK: 22 EN: 30 RU: 19

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Page language: EN

Causes

Open or shorted wiring between fuel tank C level sensor and ECM
Corroded, bent or loose connector/pins at the sensor or harness
Failed fuel level sender (float or potentiometer) in tank C
Poor or intermittent ground at the sensor
Water or contamination in connector or tank
ECM input circuit fault (less common)

Symptoms

Incorrect or no fuel level indication for alternative tank C
Fuel low or tank C warnings or messages on dash
MIL/Check Engine Light illuminated
Erratic fuel gauge behavior (jumping or intermittent)
Possible inability to switch to/use alternative tank if vehicle manages multiple tanks

What to check

Scan for stored/active codes and view freeze-frame / PID data for tank C fuel level
Visually inspect sensor connector and wiring along routing to body/ECM for damage or corrosion
Check connector pins for bent, corroded, pushed-out or broken terminals
Backprobe sensor connector and check reference voltage (key ON), signal voltage, and ground
Measure sender resistance while moving the float (with connector disconnected) and compare to expected behavior
Perform wiggle test on harness while monitoring signal for intermittent changes

Signal parameters

Reference supply typically 5 V (approx. 4.5–5.5 V) from ECM (verify for vehicle)
Sender output typically 0.5–4.5 V across float travel (varies by design) or a variable resistance style sender
Typical resistive sender ranges commonly 0–90 Ω or 0–300 Ω depending on manufacturer (verify service data)
Look for stable DC voltage or smooth resistance change as float moves; sudden drops to 0 V or battery voltage suggest short/open

Diagnostic algorithm

Retrieve P2A64 and any related codes; record freeze-frame and live data for tank C level sensor with key ON and engine running if required.
Visually inspect the fuel tank C sender harness, connectors, and routing for abrasion, pinching, corrosion, or water intrusion. Repair any obvious damage.
With key ON, backprobe the sender connector: verify reference voltage from ECM, verify good ground, and measure signal voltage. Compare to expected signal parameters.
With connector disconnected, measure sender resistance across terminals while moving the float. Resistance should change smoothly across travel. Replace sender if open, shorted, or erratic.
Perform a continuity check from ECM connector to sensor connector for each wire to confirm no opens or shorts to ground/battery. Repair broken wires or chafed sections.
Reconnect and perform a wiggle test on the harness while watching live PID/signal for intermittent faults. If intermittent, repair or replace harness/connector.
If wiring and sensor check good, test ECM input pin for proper operation or consult manufacturer diagnostic steps; replace ECM only after confirming upstream circuit is good.
After repairs, clear codes and complete required drive cycle or relearn procedure, then verify code does not return and gauge behaves normally.

Likely causes

Damaged wiring or connector at the fuel tank C sender (most common)
Corroded or poor ground connection
Failed level sensor (worn potentiometer or stuck float)
Intermittent short to battery or to ground caused by chafed harness
ECM fault (least common)

Fault status

⚠️ Status

Alternative Fuel Tank C Level Sensor Circuit — signal out of range, open, shorted or intermittent. Inspect tank C sender, wiring, connectors and grounds.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1-3 hours