P1428
EGR Temperature Sensor 1 Intake Air Temperature 2 Not Plausible
What it means
P1428. EGR Temperature Sensor 1 Intake Air Temperature 2 Not Plausible. This Chevy-enhanced code applies to Silverado 2500HD, Sierra 2500HD, Silverado 3500HD, Sierra 3500HD Duramax Diesel.
Findings, check these first
- Failed EGR cooler temperature sensor 1 reading out of plausibility range
- Soot-fouled EGR temperature sensor tip on high-mileage Duramax engines
- Chafed EGR temperature sensor harness near the hot-side turbo plumbing
- Stuck-open EGR valve skewing cooler temperature versus intake air temperature
Standard procedure
- Compare EGR temperature sensor 1 against IAT sensor 2 on a cold soak with a GDS2
- Inspect the sensor tip for soot packing before ordering parts
- Check the sensor harness for heat damage near the turbo and EGR cooler
- Test EGR valve operation since a stuck valve skews the plausibility check
- Check for ECM calibration updates covering EGR temperature rationality
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Sources and review
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Last updated 2026-09-19.
Report a correction for P1428. Include your vehicle, the issue and a source if you have one.