P01B1 code meaning
Alternative Fuel Tank A Level Sensor Circuit Low
Powertrain system Generic code P01xx codes Check engine light
What P01B1 means
These codes only apply to vehicles with a gaseous alternative fuel – compressed natural gas (CNG) or LPG – as bi-fuel models alongside gasoline or as dedicated gas engines; on bi-fuel vehicles a fault usually blocks gas operation and the vehicle runs on gasoline. Tank level sensor A only exists where there is a real sender – typically LPG tanks with a float whose position is transmitted magnetically through the tank wall (Roush propane systems: 0.1–4.9 V). With CNG the 'level' is a calculated value. The documented systems report level faults under the gasoline fuel level codes (Roush propane P0460–P0463, GM CNG van P0463), so no manufacturer document using exactly this code was found. P01B1 means the signal voltage is below its lower limit – typically a signal wire shorted to ground or a missing reference.
P01B1 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P01B1
- Check engine light on
- Gas level display wrong, jumping or empty
- Range or refuelling information unreliable
Common causes of P01B1
- Most likelySignal wire shorted to ground
- PossibleSensor shorted internally
- PossibleMoisture or corrosion in the connector
- Less likelyGas or engine module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Alternative fuel tank level sensorSensor wiring
What each part of P01B1 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 1 | Area: fuel and air metering. |
| B1 | The exact fault in that area. |
What to do next
- Note P01B1 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P01B1
What does P01B1 mean?
P01B1 means "Alternative Fuel Tank A Level Sensor Circuit Low". These codes only apply to vehicles with a gaseous alternative fuel – compressed natural gas (CNG) or LPG – as bi-fuel models alongside gasoline or as dedicated gas engines; on bi-fuel vehicles a fault usually blocks gas operation and the vehicle runs on gasoline. It is a generic code, so it means the same on every make.
Is it safe to drive with P01B1?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P01B1 fail an emissions test?
Yes, it can. P01B1 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P01B1 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P01B1 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.