What it means
Same as P24AC with the feedback 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 EGR cooler coolant pump feedback circuit tells the control module whether the pump is turning, often by reporting speed. The module sets P24AD when that feedback signal reads high, which can result from the signal wire shorting to supply voltage. The high reading can prevent the module from reliably confirming pump operation and coolant circulation.
Common causes
Most likely first.
- Feedback 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 compare the pump command with feedback data to see when the signal rises high.
- Inspect the feedback harness for pinching or melted insulation where the signal wire could contact a supply wire.
- Check the pump connector for moisture, corrosion, loose fit, or a pushed-back feedback pin.
- Following the manufacturer's procedure, test for a feedback wire short to supply and wiggle the harness while monitoring the signal.
- If the wiring is sound, check pump operation and test its feedback output and the control-module input.
Common fixes
- Repair a pinched feedback wire that contacts a supply source.
- Clean and secure the pump connector or replace a damaged terminal.
- Repair melted or rubbed-through feedback-wire insulation.
- Replace the pump if its feedback output is faulty.
- Repair the control module if its feedback input is confirmed faulty.
Can I keep driving?
Keep driving to essential trips at light load until the high feedback signal is repaired, because the module may not be able to verify EGR cooler pump operation. Stop if knocking worsens or the engine overheats.
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.