What it means
A general electrical fault on EGR control circuit B — second EGR valve on engines with high-pressure and low-pressure EGR loops.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
EGR control B operates the valve in the engine’s second exhaust-gas-recirculation path, where fitted. The control module checks the electrical circuit that commands this valve and sets P045A when it detects a general circuit fault, such as an open or short, rather than a specific low- or high-signal condition.
Common causes
Most likely first.
- EGR control solenoid failure
- Open or short in the control wiring
- Corroded or loose connector
- Fault in the control module
Symptoms
- Check engine light on
- Pinging or knocking under load
- Power loss and hesitation
- Possible rough idle
- Failed emissions inspection (NOx)
How to diagnose it
- Read the freeze-frame data and any related EGR codes to see when the circuit fault occurred and whether it affects control B specifically.
- With the engine off, inspect the EGR B valve or solenoid connector for looseness, corrosion, moisture, or damaged pins.
- Trace the EGR B wiring harness for breaks, chafing, pinching, or contact with hot or moving parts.
- Use a scan tool to compare the commanded state of EGR B with available circuit or position data and note whether the fault is present or intermittent.
- Test the EGR B control circuit for continuity and shorts using the vehicle wiring diagram, then compare results with the manufacturer's specification.
- If wiring and the valve or solenoid test correctly, check the control module's circuit connections and outputs according to the manufacturer's diagnostic procedure.
Common fixes
- Reconnect and secure the EGR B connector, or clean corroded terminals where appropriate.
- Repair damaged or chafed wiring in the EGR B control circuit.
- Replace a failed EGR B control solenoid or valve after confirming the circuit fault.
- Repair or replace a control module only after its power, grounds, wiring, and output have been verified.
Can I keep driving?
You can usually drive gently if the engine runs smoothly, but avoid heavy load if it pings, hesitates, or loses power. The fault can raise NOx emissions and may cause a failed emissions inspection.
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.