What it means
Vacuum Sensor A Range/Performance: the signal is implausible or outside the valid range.
How it works
Vacuum sensor A reports vacuum level to the control module for monitoring brake assist. This code sets when the sensor A signal does not behave within the module's valid range, which can result from a sensor fault, wiring problem, or an actual vacuum supply issue.
Common causes
Most likely first.
- Vacuum sensor fault
- Wiring or connector fault
- Vacuum supply or hose problem
Symptoms
- Brake or stability-control warning light on
- Brake assist may be affected
How to diagnose it
- Scan the brake or stability module and compare sensor A's live vacuum reading with freeze-frame data and any other available vacuum readings.
- Inspect sensor A's connector and wiring for loose terminals, corrosion, damaged insulation, or intermittent contact.
- Check the vacuum hose and connections serving sensor A for disconnection, damage, blockage, or leakage.
- Observe sensor A data while gently moving its harness to see whether the reading changes unexpectedly.
- If the vacuum supply and wiring are sound, test sensor A and the module input according to the manufacturer's procedure.
Common fixes
- Reconnect or replace a damaged, leaking, or disconnected vacuum hose.
- Repair loose, corroded, or damaged sensor A wiring and connector terminals.
- Replace vacuum sensor A if its output remains implausible with a sound vacuum supply and circuit.
- Repair the module input only if testing confirms the module is at fault.
Can I keep driving?
Brake assist may be reduced if the implausible reading reflects a real vacuum problem. Pay attention to pedal effort and stopping distance, drive cautiously, and stop safely if braking becomes difficult.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.