What it means
The measured fuel injection quantity for group D is below the calibrated window. Injector flow drift, rail pressure off, or measurement bias.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The engine control module estimates the fuel delivered by injection group D and compares it with the expected operating window. This code sets when the estimated quantity for group D is lower than expected, which can happen if its injectors deliver too little fuel or fuel rail pressure is low.
Common causes
Most likely first.
- Injectors partially clogged
- Fuel rail pressure low
Symptoms
- Check-engine light
- Rough running or misfire
- Reduced power or acceleration
- Hard starting
How to diagnose it
- Use a scan tool to record freeze-frame data and compare group D injection quantity with other groups under the same conditions.
- Check whether rough running or misfire is concentrated in the cylinders served by group D, using available cylinder balance or misfire data.
- Inspect the group D injectors and their connectors and wiring for damage, contamination, or poor connections.
- Check fuel pressure data under the conditions in the freeze frame and compare actual pressure with the manufacturer's specification.
- If pressure is within specification, test group D injector flow or balance using the vehicle manufacturer's procedure.
Common fixes
- Repair a loose, damaged, or corroded injector connector or wiring in group D.
- Restore low fuel rail pressure by repairing the confirmed fuel supply or pressure-control fault.
- Clean or replace a group D injector confirmed to have restricted flow.
- Correct a verified measurement or calibration issue using the manufacturer's diagnostic procedure.
Can I keep driving?
If the engine runs roughly or lacks power, avoid hard acceleration and long trips; too little fuel to group D can worsen misfires and affect emissions. Stop driving if the engine misfires severely or the warning light flashes.
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.