A failing vacuum sensor B that produces an erratic or out-of-range signal.; Damaged, chafed, or corroded wiring between the vacuum sensor and the module that reads it.; Loose or contaminated connector pins at the sensor or at the module.; A vacuum leak or blocked vacuum passage that makes the sensor reading implausible to the module.; A software or calibration issue in the module that receives the vacuum sensor data.; A faulty module that misinterprets valid sensor data as invalid.; Low battery voltage or poor grounds that corrupt sensor signals and communication.

DTC codes / U04xx · Invalid data received from a module / U043F

U043FInvalid Data Received From Vacuum Sensor B

Q: What does code U043F mean?

Invalid Data Received From Vacuum Sensor B. U043F means the module that monitors vacuum sensor B received data from that sensor that it judged invalid, so it cannot trust the vacuum reading. The computer detected a message or signal that was out of range, implausible, or missing the expected validity information, and it has set this communication fault instead of using the reading.

U043F means the module that monitors vacuum sensor B received data from that sensor that it judged invalid, so it cannot trust the vacuum reading. The computer detected a message or signal that was out of range, implausible, or missing the expected validity information, and it has set this communication fault instead of using the reading.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaInvalid data received from a module

Symptoms you may notice

Often no symptoms besides the warning light, especially if the vacuum sensor is not used for a critical function.
Rough idle or unstable engine operation if the invalid vacuum data affects fuel or purge control.
A stored or pending U043F with no drivability complaint, sometimes accompanied by other communication codes.
Illumination of the check engine light or service vehicle soon message on the dashboard.
Reduced fuel economy or slightly elevated emissions if the module substitutes a default vacuum value.
Intermittent warning light that comes and goes with temperature or vibration.

Common causes, most likely first

A failing vacuum sensor B that produces an erratic or out-of-range signal.
Damaged, chafed, or corroded wiring between the vacuum sensor and the module that reads it.
Loose or contaminated connector pins at the sensor or at the module.
A vacuum leak or blocked vacuum passage that makes the sensor reading implausible to the module.
A software or calibration issue in the module that receives the vacuum sensor data.
A faulty module that misinterprets valid sensor data as invalid.
Low battery voltage or poor grounds that corrupt sensor signals and communication.

How to diagnose and fix it

Scan all modules for stored and pending codes, and record freeze-frame data for U043F before clearing anything.
Inspect the vacuum sensor B connector and the module connector for corrosion, loose pins, or pushed-back terminals.
Check the sensor's reference voltage, ground, and signal wire with a multimeter and compare to the manufacturer's specification.
Inspect vacuum hoses and passages for leaks, cracks, or blockage that could make the sensor reading implausible.
Verify battery voltage and ground integrity, then clear the code and test-drive to see if it returns.
If the signal is correct at the sensor but the module still reports invalid data, follow the manufacturer's diagnostic flow for the communication circuit or module.
Replace the vacuum sensor only after electrical and vacuum checks confirm it is the source of the invalid data.

What the invalid data actually means

U043F is a communication fault, not a direct sensor performance code, so replacing the vacuum sensor without checking the circuit often does not fix it.
A vacuum leak can make a healthy sensor report a value the module considers implausible, so the sensor itself may not be at fault.
This code can be set by a module that receives vacuum data over a network, meaning the fault may lie in the sending module rather than the sensor.
Intermittent U043F codes are frequently caused by connector fretting or vibration rather than a failed sensor.
Clearing the code without checking freeze-frame data can erase the conditions that would point to the real cause.

Can I keep driving with U043F?

You can usually keep driving with U043F because the module substitutes a default value, but avoid towing heavy loads or relying on vacuum-assisted systems until it is diagnosed. If the engine runs rough or the brake pedal feels firm, stop driving and have it inspected promptly.

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 all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.