What it means
The internal power-down timer of the engine controller does not run as expected. The module either stays awake too long after key-off (battery drain) or shuts down too early (no aftertreatment cool-down or learn-write).
At a glance
- Usually lights the check-engine light
How it works
The engine control module uses an internal timer to manage how it powers down after the ignition is switched off. P262B means that shutdown timing is not performing as expected, such as the module staying awake too long or shutting down before its normal tasks finish. A relay interruption or an internal timer problem can cause this fault and may lead to a discharged battery.
Common causes
Most likely first.
- Intermittent main relay opens early
- Software timer counter corrupted
Symptoms
- Check-engine light
- Battery may discharge after the vehicle is parked
How to diagnose it
- Check freeze-frame data and related power-supply codes, and note whether the battery drains after the vehicle is parked.
- Inspect the engine control module's main relay, fuse connections, and related wiring for looseness, corrosion, or heat damage.
- With the vehicle secured, observe module power and network activity after key-off using suitable scan equipment to confirm whether shutdown timing is abnormal.
- Check the main relay supply and control circuit for intermittent opens during the shutdown period.
- If the power supply stays stable, verify module software status and timer operation using the manufacturer's diagnostic information.
- After any repair or update, confirm the module shuts down normally and the parked vehicle no longer shows the reported battery drain.
Common fixes
- Clean and secure corroded or loose main-relay and fuse connections.
- Replace an intermittent main relay after confirming it opens during module shutdown.
- Repair damaged relay control or power wiring.
- Apply a manufacturer-approved module software update if it addresses the timer fault.
- Replace the control module only if its internal timer fault is confirmed.
Can I keep driving?
The vehicle may remain drivable, but a module that stays awake can discharge the battery and leave you unable to start; an early shutdown may interrupt stored learning or aftertreatment tasks. Arrange diagnosis soon if the battery is draining.
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.