Loose, corroded or damaged connector at the tank level sensor or its multiplug; Chafed, broken or intermittently open or shorted wiring between the level sensor and the control unit; Failing alternative fuel tank level sensor, such as a worn track or sender fault; Poor earth or reference supply affecting the sensor signal; Moisture or contamination in the tank-mounted connector or multivalve assembly; Fault in the control unit or gas system module that reads the sensor; Outdated or faulty control unit software where the manufacturer has identified it as a known cause.

P01B3

Alternative Fuel Tank A Level Sensor Circuit Intermittent/Erratic.

Generic
Powertrain
Generic code
Low severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
1: AreaFuel and air metering
B3: FaultThe specific fault in that area

What it means

P01B3 is a generic code meaning the control unit has seen an intermittent or erratic signal from the level sensor circuit for alternative fuel tank A, such as the LPG, CNG or other non-petrol/diesel fuel tank. The signal has jumped, dropped out or changed in a way that does not match a real change in fuel level. The exact sensor type, signal range and monitoring conditions depend on the vehicle and the alternative fuel system fitted.

Symptoms

Malfunction indicator lamp on
Alternative fuel gauge reading erratically, jumping or dropping to empty
Fuel level display freezing or showing incorrect range
Unexpected switch back to petrol or the primary fuel
Alternative fuel mode unavailable or reduced range warning appearing wrongly

Possible causes

Loose, corroded or damaged connector at the tank level sensor or its multipluglikely
Chafed, broken or intermittently open or shorted wiring between the level sensor and the control unitlikely
Failing alternative fuel tank level sensor, such as a worn track or sender faultlikely
Poor earth or reference supply affecting the sensor signalpossible
Moisture or contamination in the tank-mounted connector or multivalve assemblypossible
Fault in the control unit or gas system module that reads the sensorrare
Outdated or faulty control unit software where the manufacturer has identified it as a known causerare

How to diagnose

Read all stored and pending codes and note the freeze frame data, including conditions when the fault set
Check for other fuel level, supply voltage or alternative fuel system codes that point to a common cause
Inspect the level sensor wiring and connectors for damage, corrosion, water ingress, chafing and poor pin tension, and wiggle test the harness while watching live level data
Watch the live alternative fuel level reading and compare it with the actual fuel quantity to see if it jumps or drops out
Check the sensor supply, reference and earth circuits against the manufacturer's wiring information
Measure the sensor signal and resistance across its range and compare with the specification for that model
Test the wiring for continuity and for shorts to earth or supply, with the control unit disconnected as per the manufacturer's procedure
Check for any applicable software updates or technical service bulletins for that model

How to fix

Clean, repair or replace the affected connector and terminals, and seal against moisture
Repair or replace damaged wiring and secure it clear of heat and sharp edges
Replace the alternative fuel tank level sensor or sender assembly, following the correct safety procedures for gas systems
Restore faulty earth or supply connections
Replace or reprogram the control unit only after the wiring and sensor are proven good, and update the calibration only if an outdated one is a known cause

Can I keep driving?

Low severity

The car can usually be driven and will normally run on petrol or its primary fuel, but the alternative fuel gauge may be unreliable so do not rely on it. Book it in soon, and have it checked promptly if you smell gas or notice any fuel leak.

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