P24C4EGR Cooler Bypass Position Sensor Exceeded Learning Limit Bank 1
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- The bypass flap of the EGR cooler learns its end stops, and P24C4 means the learned values for bank 1 have left the window the software accepts. GM's diesel tables from 2017 on run the learning after key-off with coolant between 70 and 129 °C: the raw signal must lie between 16 and 24 % of 5 V in cooling position and between 72 and 85 % in bypass position; outside, the code is stored as Type B. GM's 2014 table 14OBDG10 instead judges the spread of the learned offsets (over 50 %) and a single offset beyond about ±16 %. Bulletin PI1449 for the 2015 Silverado and Sierra with the LML Duramax pairs it with P2493, P2495 and P06A3 and calls for a complete new bypass valve. Pure circuit faults are P2494/P2495; bank 2 reports P24C5.
- What you may notice
- Malfunction indicator lamp on after the second trip
- Reduced EGR cooling, higher NOx output
- Often no change in driveability
- Likely causes
- LikelyWorn bypass valve whose integrated position sensor no longer reaches its learned values
- PossibleSoot deposits shifting the end stops of the flap
- PossibleSignal offset from connector corrosion or a weak 5 V reference
- RareLearning repeatedly cut short because the controller is woken right after key-off
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €250 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.