Cold Start Emission Reduction Control System
What it means
P1400. Cold Start Emission Reduction Control System. This Chevy-enhanced code applies to Silverado, Sierra, Equinox, Terrain, Malibu, Cruze.
Findings, check these first
- Carbon-fouled throttle body skewing the cold-start airflow model
- Weak or aging upstream oxygen sensors slowing catalyst light-off feedback
- Engine coolant temperature sensor reading low, preventing cold-start strategy entry
- Aftermarket cold-air intake altering modeled cold-start airflow
Standard procedure
- Scan cold-start freeze-frame data (ECT, IAT, spark advance, idle speed) with a Tech2/GDS2 scan tool
- Clean the throttle body and perform an idle relearn before replacing parts
- Test the ECT and IAT sensors against actual ambient temperature on a cold soak
- Check for Technical Service Bulletins on cold-start calibration updates for the model year
- Reflash the ECM with the latest calibration if all sensors test normal
Look up another code
Press / to jump to the box. Chevy-enhanced powertrain, body, chassis and network codes.
Sources and review
Review: checked against the recorded source material.
- Code P1400 2015 GMC Sierra Cold Start Emission Reduction Control System
archived reference page (autocodes.com via Wayback Machine)
Supports: code identity, GM application, and 2015 GMC Sierra fitment
Fetched directly. The GMC page names cold start emission reduction control system and states the 2015 Sierra application, matching the catalog. The engine-codes generic P1400 page is Ford DPFE. Other model fitment remains curator claims.
Last updated 2026-09-13.
Report a correction for P1400. Include your vehicle, the issue and a source if you have one.