P23E7EGR C Flow Insufficient Detected
- 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
- P23E7 means the module calculates less recirculated exhaust through path C than it expects for the current operating point. The valve may well move correctly; the gas simply does not get through, for example because the passage, cooler or valve seat is choked with soot. GM's 2018 diesel tables illustrate the A-side check P0401: measured air mass is compared with a value expected with EGR active, corrected for barometric pressure, and only at steady speed and fuelling, coolant above 60 °C, outside air above −7 °C and ambient pressure above 74.8 kPa; it is Type B after 350 failures. CARB requires low EGR flow to be detected before NOx exceeds its limits. No manufacturer documents P23E7 publicly. Excess flow is P23E8; valve C stuck closed is P23E6.
- What you may notice
- Warning lamp after steady cruising
- Raised NOx at emissions testing
- Likely causes
- LikelySoot-choked EGR passage or valve seat on path C
- PossibleClogged EGR cooler in path C
- RareAir mass or pressure sensor reading off, skewing the calculation
- 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: €100 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.