P24EF
Control Module Wake-up Circuit/Open
The wake-up line that brings a sleeping ECU back from low-power mode is open. Many networks use a dedicated hardware wake-up wire (door-latch trigger, terminal 15, CAN wake-up) so modules can stay asleep with the ignition off. Without it, the module either fails to wake up at start-up or stays awake and drains the battery.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Broken wake-up wire or unplugged connectorCommon
- Failed wake-up input stage in the modulePossible
- Pin pushed back out of connector bodyLess likely
Parts involved
- Wake Up Circuit
- Control Module
- Wiring Harness
P24EF is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.