What it means
Same as P245A with the control line shorted to supply. EGR mixes inert exhaust into intake to lower combustion peak temperature — too little raises NOx, too much causes misfires and rough running.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The bank 1 EGR cooler bypass valve routes exhaust around the cooler when commanded. The control module monitors its electrical control signal and sets P245D when the signal is higher than expected, often because the control wire is shorted to a supply or pinched against a powered circuit.
Common causes
Most likely first.
- Control line shorted to supply
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
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
- Record freeze-frame data and check for other bank 1 bypass or supply-voltage codes that could indicate a shared wiring problem.
- Inspect the bank 1 bypass-valve connector for backed-out pins, corrosion, heat damage, or contact with a powered wire.
- Trace the control harness and look for insulation rubbed through or pinched against a battery-positive or other supply wire.
- Measure the control-circuit signal and check for a short to supply using the manufacturer's circuit test procedure.
- If the harness and connector are sound, test the actuator and module output against the manufacturer's specification.
Common fixes
- Repair a control wire shorted to a supply or pinched against a powered circuit.
- Replace damaged connector terminals and secure the bank 1 bypass-valve connection.
- Replace a faulty bank 1 bypass actuator if the wiring tests correctly.
- Repair a confirmed module output fault.
Can I keep driving?
Drive gently and avoid heavy load if the engine knocks, hesitates, or loses power. The bypass valve may not respond correctly, which can affect engine operation and emissions.
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.