Code
P1433
PONTIAC
P — Powertrain
Fuel Level Sensor 2 Circuit High Voltage
AI status
Completed
Completed
100%
Causes
- Open or damaged wiring in the Fuel Level Sensor 2 signal circuit
- Short to battery/constant 12V on the signal circuit
- Corroded or loose connector at the fuel level sender or fuel tank module
- Faulty fuel level sender (stuck float or failed variable resistor)
- Faulty ground or reference circuit to the sender
- PCM (powertrain control module) internal fault or poor connector at PCM
Symptoms
- Malfunction Indicator Lamp (MIL) / Check Engine Light illuminated
- Fuel gauge reads full or erratic on cluster for the affected tank/sender
- Inaccurate fuel level readings or sudden jumps in displayed fuel level
- Possible difficulty estimating remaining range; no direct drivability issues in most cases
What to check
- Read and record freeze-frame and stored data with a scan tool; confirm P1433 and any related codes
- Verify vehicle VIN and body/style to confirm multiple fuel senders (some models have two senders or dual-tank systems)
- Monitor live data for Fuel Level Sensor 2 while operating and key on engine off (KOEO) — note voltage or percent value and whether it is steady or jumps
- Visually inspect connectors and wiring at the rear tank module/filler neck area for damage, corrosion, or water intrusion
- Backprobe the sender connector to verify reference voltage (usually 5V) and signal voltage to PCM with key on
- Check for proper ground at the sender and continuity to PCM ground/connector pins
Signal parameters
- Typical sender uses a variable resistor providing a signal between ~0–5.0 V (or a resistive value that changes smoothly with float travel).
- High-voltage condition generally means the signal is near supply voltage (e.g., >4.5–4.8 V) or the resistance is outside expected upper range.
- Resistance of the sender should change smoothly as the float is moved; exact ohm values vary by model (consult OE service data for exact specs).
- Reference supply from PCM commonly ~5 V; verify 5 V reference present on the connector pin with key on.
Diagnostic algorithm
- Confirm the DTC and note whether it is current, pending, or historic. Check for related codes (fuel level, grounds, communication).
- With key OFF, visually inspect fuel tank sender connector and wiring for damage, corrosion or pin contamination. Repair any obvious issues.
- Turn ignition to ON (engine OFF). Backprobe the sender connector: measure reference voltage (expect ~5 V) and signal voltage. Record values. If signal is high (~near reference or battery voltage) the fault is present.
- Move the sender float (if accessible) or physically actuate the sender while watching live data. The signal should move smoothly; if it remains high or erratic, suspect sender or wiring.
- Disconnect the sender connector. On most systems disconnecting the sender will cause the PCM to see an open or default value; observe how the signal and code behave. If disconnecting changes the reading to the expected open-circuit/default but the code returns when reconnected, focus on sender or connector.
- Perform continuity checks between the sender signal pin and PCM pin; check for short to battery (measure voltage on wiring with connector disconnected) and short to ground. Repair any shorts or opens.
- Inspect and test the ground circuit for the sender: measure continuity from sender ground to chassis and PCM ground; repair poor ground connections.
- If wiring and connector test OK and sender resistance does not change correctly, remove tank module or sender and bench-test/replace the sender per OEM procedure.
- Clear codes, perform relevant drive cycle or ignition cycles and verify the code does not return. If the problem persists after wiring and sender replacement, test or replace the PCM per manufacturer procedures.
Likely causes
- Short to B+ on the sender signal or reference wire
- Corroded/loose sender connector allowing intermittent high-voltage reading
- Failed fuel level sender (resistance stuck at high-voltage position)
- Damaged wiring harness near the tank (chafing, rodent damage)
- Bad ground or missing reference voltage from PCM (less common)
Fault status
Status
Fuel Level Sensor 2 Circuit High Voltage — signal voltage above expected range on the secondary fuel level sender circuit; possible short to battery, faulty sender, or wiring/connector fault.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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