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DTC codes / GM codes / P1432

P1432 · GMFuel Level Sensor 2 Circuit Low Voltage

P1432 on a GM vehicle means the powertrain control module (PCM) has detected a low voltage signal on the fuel level sensor 2 circuit, which is the secondary fuel level sender used on vehicles with dual tanks or a transfer pump system. The PCM monitors the signal voltage from the sensor and sets this code when the voltage stays below the expected threshold for a calibrated amount of time, indicating a short to ground, an open circuit, or a failed sensor.

SystemPowertrain
Code typeGM specific
SeverityLow
Fix difficultyIntermediate
AreaAuxiliary emission controls

Symptoms you may notice

  • The check engine light or service engine soon light is illuminated on the instrument cluster.
  • The fuel gauge may read incorrectly, often showing empty or fluctuating when the tank is not actually empty.
  • A message such as 'Fuel Level Low' may appear on the driver information center even when fuel is present.
  • The vehicle may run out of fuel unexpectedly if the gauge is relied upon for refueling decisions.
  • Often no symptoms besides the warning light, especially if the primary fuel level sensor still provides a usable signal.
  • On some GM trucks and SUVs, the fuel gauge may default to a fixed position or sweep erratically during driving.

Common causes, most likely first

  1. A short to ground in the fuel level sensor 2 signal circuit, often from chafed wiring near the fuel tank or along the frame rail.
  2. A failed fuel level sensor 2 inside the secondary tank or on the transfer pump assembly, typically due to wear on the resistive track or a faulty float.
  3. Corroded or loose electrical connector at the fuel tank module or inline harness connector, allowing the signal voltage to drop.
  4. An open circuit in the sensor ground or reference voltage circuit shared with the fuel level sensor 2.
  5. Water intrusion into the connector or sensor assembly causing a low-resistance path to ground.
  6. A faulty fuel pump control module or body control module (BCM) on vehicles where the fuel level signal is routed through a module before reaching the PCM.
  7. Aftermarket accessories or improper wiring repairs that tap into the fuel level circuit and load it down.

How to diagnose and fix it

  1. Connect a scan tool and read the fuel level sensor 2 voltage and fuel tank level parameters to confirm the low voltage condition and check for other stored codes.
  2. Visually inspect the fuel level sensor 2 wiring harness and connectors at the tank and along the frame for chafing, corrosion, or loose pins, and repair as needed.
  3. Disconnect the fuel level sensor 2 connector and measure resistance across the sensor terminals; compare to the factory specification for the indicated fuel level.
  4. Check the signal circuit for a short to ground by measuring resistance from the sensor signal wire to chassis ground with the sensor disconnected.
  5. Check the reference voltage and ground circuits at the sensor connector with the key on, engine off, to verify the PCM is supplying the correct voltage.
  6. If the sensor resistance is out of specification or the float is damaged, replace the fuel level sensor 2 or the fuel pump module assembly as required.
  7. Clear the diagnostic trouble codes and verify the fuel gauge operates correctly through a full sweep or by adding fuel and monitoring the scan tool data.

What GM techs check before replacing the sender

  • On GM vehicles with dual fuel tanks, the secondary fuel level sensor is often part of the transfer pump assembly, and a failed transfer pump can cause the sensor to read low even when the sensor itself is good.
  • A common misdiagnosis is replacing the fuel level sensor when the real problem is a chafed signal wire behind the fuel tank shield or near the spare tire mount, which is easy to miss during a quick visual inspection.
  • The PCM may set P1432 intermittently if the fuel level is very low and the vehicle is on an incline, so verify the code returns under normal driving conditions before condemning parts.
  • On some GM trucks, the fuel level signal passes through the body control module (BCM) before reaching the PCM, and a BCM fault or communication issue can set this code without any problem in the sensor circuit.
  • Aftermarket fuel pump assemblies sometimes have incorrect resistance values for the secondary sensor, causing P1432 to set even though the new part appears to function on the bench.

Can I keep driving with P1432?

You can generally continue driving with P1432 because it does not affect engine operation or safety systems, but do not rely on the fuel gauge for refueling decisions until the fault is repaired. Avoid running the tank very low, as an inaccurate gauge could leave you stranded.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for GM vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

Running on fumes Free guides aren't free to make. Top up the tank. Any amount, one time. Fuel the Garage