What it means
The injection pulse offset adaptation for cylinder 7 exceeds the calibrated learning window. Injector aging or fuel pressure drift beyond compensation.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The ECM learns a separate injection pulse offset for each cylinder to balance combustion. P2B1D means the correction needed for cylinder 7 exceeds the permitted learning window, which can indicate a worn cylinder 7 injector or fuel rail pressure drift beyond the ECM's ability to compensate.
Common causes
Most likely first.
- Injector worn beyond compensation range
- Fuel rail pressure drift
Symptoms
- Check-engine light
- Rough idle or engine vibration
- Reduced engine performance
How to diagnose it
- Read freeze-frame data and related codes, noting engine load and fuel rail pressure when the cylinder 7 correction exceeded its learning window.
- Review live cylinder-balance or injector-correction data to see whether cylinder 7 is the outlier or whether multiple cylinders point to a shared fuel pressure issue.
- Inspect the cylinder 7 injector connector and wiring for damage or poor contact, and check for fuel leaks or signs of recent injector work.
- Compare commanded and measured fuel rail pressure under relevant operating conditions with the manufacturer's specification.
- Test cylinder 7 injector operation and delivery using the vehicle's specified procedure, comparing results with the manufacturer's specification.
- Repair the confirmed cause, then clear the code and verify the cylinder 7 correction stays within its learning window.
Common fixes
- Repair a poor connection or damaged wiring at the cylinder 7 injector.
- Correct a confirmed fuel rail pressure control or supply fault.
- Replace the cylinder 7 injector if testing confirms it is worn beyond the permitted correction range.
- Perform any required cylinder 7 injector coding or adaptation after repair.
Can I keep driving?
Avoid hard acceleration and long trips if the engine vibrates or has reduced power; continued operation can worsen drivability and increase emissions. Stop if it runs severely rough or loses significant power, and have the cylinder 7 injector correction and fuel pressure checked promptly.
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.