What it means
The control module monitors the circuit for brake pressure sensor E. It sets this code when the circuit is detected as open and the sensor signal is unavailable.
At a glance
- Usually lights the ABS or stability-control warning light
- The engine or gearbox may go into limp mode
How it works
Brake pressure sensor E supplies a pressure signal to the brake control module through a monitored circuit. C05A1 sets when the module detects an open circuit and cannot receive sensor E's signal, for example from a broken wire or a terminal pushed out of its connector.
Common causes
Most likely first.
- Wire broken
- Pin pushed back out of connector body
- Cracked solder joint inside the module or sensor
Symptoms
- ABS warning light on
- ESC/stability control deactivated
- Possible reduced brake assist
- Speedometer may behave erratically
How to diagnose it
- Read ABS codes, freeze-frame data, and live sensor E data to confirm the signal is unavailable and check for related circuit faults.
- Inspect sensor E's connector for a pushed-back pin, poor seating, corrosion, or damage, and examine the harness for a break.
- Check the relevant fuse or supply where specified by the wiring diagram, since loss of sensor power can also make its signal unavailable.
- With the circuit powered down as specified by the manufacturer, test sensor E circuit continuity and connector contact to locate an open.
- If the harness and connectors pass, test sensor E and the brake module for an internal open or connection fault using the manufacturer's procedure.
Common fixes
- Reconnect sensor E's loose connector and secure it properly.
- Repair a broken wire or replace a damaged connector terminal.
- Restore a failed supply connection or fuse after finding the cause of the open circuit.
- Repair or replace sensor E or the brake module only if testing confirms an internal fault.
Can I keep driving?
With sensor E's signal unavailable, ABS and stability functions may be disabled and brake assist may be reduced. Drive only if the brakes feel normal, allow extra stopping distance, and stop if braking changes or additional brake warnings appear.
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.