Faulty second fuel level sender (worn resistive track or failed float arm) in the tank; Damaged wiring, corroded terminals or poor connector contact on the sender circuit, often near the tank or under the vehicle; Sender float stuck, bent or fouled, or the sender mounting damaged inside the tank; Transfer of fuel between tank halves not working correctly (for example a faulty jet pump or transfer line on a saddle tank), so the second sensor reading is not plausible; Poor earth connection or a reference voltage fault shared with the other fuel level circuit; Fault in the powertrain control module or instrument cluster interpreting the signal.

P1431

Fuel Level Sensor 2 Performance.

Oldsmobile
Powertrain
Manufacturer code
Low severity

How this code is built

P: SystemPowertrain
1: Defined byThe manufacturer
4: AreaAuxiliary emission controls
31: FaultThe specific fault in that area

What it means

On Oldsmobile (GM-family) vehicles, P1431 means the powertrain control module has judged the second fuel level sensor's signal to be implausible or not behaving as expected. This usually applies to vehicles with a two-part or saddle-type fuel tank where a second sender reports the level in the other half. The module saw the sensor's reading fail to change, change too slowly, or disagree with the first sensor or with fuel used.

Symptoms

Fuel gauge reading incorrectly, stuck, or fluctuating
Fuel gauge not reaching full after filling up
Low fuel warning light coming on at the wrong time
Malfunction indicator lamp on
Gauge reading dropping suddenly or jumping between levels

Possible causes

Faulty second fuel level sender (worn resistive track or failed float arm) in the tanklikely
Damaged wiring, corroded terminals or poor connector contact on the sender circuit, often near the tank or under the vehiclelikely
Sender float stuck, bent or fouled, or the sender mounting damaged inside the tankpossible
Transfer of fuel between tank halves not working correctly (for example a faulty jet pump or transfer line on a saddle tank), so the second sensor reading is not plausiblepossible
Poor earth connection or a reference voltage fault shared with the other fuel level circuitpossible
Fault in the powertrain control module or instrument cluster interpreting the signalrare

How to diagnose

Read all stored codes and freeze frame data, and note whether other fuel level sensor codes are also present
Compare the fuel gauge reading with the known amount of fuel in the tank, and note whether it behaves differently when the tank is full, half full or nearly empty
Inspect the wiring and connectors for the second fuel level sensor for chafing, water ingress, corrosion and pushed-back pins
Using a scan tool's live data, watch the second fuel level sensor reading while the fuel level changes, and compare it with the first sensor
Check the sender circuit's reference voltage, signal and earth with a multimeter against the manufacturer's wiring diagram
Measure the sender's resistance across its range of float travel and compare it with the specification for your model
Inspect the sender and float in the tank for damage or sticking, and check the fuel transfer arrangement on saddle-type tanks
Check the earth points and clear the code, then road test to see if it returns

How to fix

Replace the faulty second fuel level sender or sender assembly
Repair or replace damaged wiring, and clean or replace corroded connector terminals
Free, straighten or replace a stuck or damaged float arm
Repair the fuel transfer arrangement between the tank halves if it is faulty
Restore poor earth connections
Replace or have the control module checked only after the sender, wiring and earths have been proven good

Can I keep driving?

Low severity

The car is normally safe to drive, but the fuel gauge may be unreliable, so keep track of fuel used by mileage to avoid running out. Book it in for repair soon.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.