What it means
The supply voltage feeding injector group B has dropped below the lower limit. The injectors in this group lose drive voltage and may stop firing, so the cylinders they serve run lean or cut out. Causes: a blown fuse, a failed injector supply relay, a voltage drop in the supply harness, or a poor ground or connector on the group-B supply.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Injector group B shares a power supply that lets its injectors open when commanded by the engine control module. This code sets when the module detects that the group B supply voltage is below its expected lower limit, which can prevent those injectors from operating reliably.
Common causes
Most likely first.
- Fuse, relay, or wiring fault on supply
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
Symptoms
- Check engine light on
- Misfire or rough idle on the affected cylinder
- Increased fuel consumption
- Possible fuel smell or smoke from exhaust
How to diagnose it
- Use a scan tool to record freeze-frame data and check which cylinders show misfires, since this helps identify the group B effects and when the voltage fault occurred.
- Inspect the group B fuse, supply relay, connectors, and harness for a blown fuse, corrosion, loose pins, or chafing.
- With the fault present, measure voltage at the group B supply and compare it with the manufacturer's specification.
- Check voltage drop across the group B supply wiring and connector under load to find high resistance.
- If the supply wiring and connections pass, test the relay and its control circuit, then check the module output according to the vehicle's service information.
Common fixes
- Clean and secure corroded or loose group B supply connector pins.
- Repair chafed or high-resistance wiring in the group B supply harness.
- Replace a blown fuse after finding and correcting the cause.
- Replace a failed injector supply relay.
Can I keep driving?
Avoid driving if the engine is misfiring badly, running roughly, or producing fuel-smelling exhaust; unburned fuel can damage the catalytic converter. If it runs smoothly, limit driving and have the group B supply fault 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.