What it means
The control circuit of camshaft profile actuator B on the exhaust side of bank 1 reports a control circuit/open condition. Cam profile B (high-lift or VTEC-style) cannot be commanded reliably.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
- The engine or gearbox may go into limp mode
How it works
Actuator B controls the alternate, higher-lift profile of the exhaust cam on bank 1. The control module monitors its electrical circuit and sets P2B39 when it detects an open path, preventing reliable control of that exhaust cam profile.
Common causes
Most likely first.
- Open in actuator control wire
- Open actuator coil
- Pin pushed back out of connector body
Symptoms
- Check engine light on
- Power loss especially in mid-rpm range
- Possible rough idle or stalling
- Increased fuel consumption
How to diagnose it
- Record freeze-frame data and check live data for the bank 1 exhaust profile command and related actuator faults.
- Inspect the bank 1 exhaust actuator B connector for a pushed-back pin, poor fit, corrosion, or heat-damaged wiring.
- With the ignition off and circuit isolated as specified by the manufacturer, check the actuator control wire for continuity.
- Measure actuator B's coil and compare the result with the manufacturer's specification to find an open coil.
- If the wire and coil pass, follow the manufacturer's circuit test to check the module connection and actuator response.
Common fixes
- Reconnect the bank 1 exhaust actuator B connector and secure any displaced terminal.
- Repair an open or damaged section of the actuator control wire.
- Replace actuator B if its coil is open.
- Repair a module connection if testing identifies it as the cause.
Can I keep driving?
A short, gentle drive may be possible if the engine runs smoothly, but avoid hard acceleration because the bank 1 exhaust cam may not switch profiles. Stop if the engine stalls or runs roughly, as drivability and fuel economy can deteriorate.
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.