What is Cold Start Emission Reduction Strategy (CSERS)?

< Back to All
Tags: , ,

Research shows that an internal combustion engine vehicle produces the greatest amount of harmful emissions during the initial starting and warmup of the vehicle.  This is due to the aftertreatment system being the most efficient when it is at normal exhaust gas operating temperatures.  Once the aftertreatment system is fully warm, it is very effective at reducing tailpipe emissions.  In an attempt to reduce these harmful emissions during a cold start, the California Air Resources Board (CARB) added cold start requirement to the 1968.2 regulation which states: “For all 2006 through 2008 model year Low Emission Vehicle II applications and all 2009 and subsequent model year applications, if a vehicle incorporates a specific engine control strategy to reduce cold start emissions, the OBD II system shall monitor the commanded elements/components for proper function (e.g., increased engine idle speed, commanded ignition timing retard), other than secondary air, while the control strategy is active to ensure proper operation of the control strategy. Secondary air systems shall be monitored under the provisions of section (e)(5).” (CARB, Section 11.1.1.)

Vehicles produce the greatest amount of harmful emissions during the initial starting and warmup

CSERS has been a hot topic in the world of CARB OBD for the last few years.  It seems that many manufacturers have missed the intent of the CARB CSERS regulation, and some have received extra scrutiny from CARB staff.  The primary intent of the CSERS regulation is to monitor catalyst heating in order to reduce cold engine out emissions.  More specifically to quote CARB’s Initial Statement of Reasons (ISOR 2002), the original purpose of the CSERS regulation requirement is “to monitor the key parameters used to implement cold start emission reduction strategies.  This would ensure that the target conditions necessary to reduce emissions or catalyst light-off time are indeed achieved” (CARB, Page 24).

WinterPark wants to help manufacturers gain a better understanding of the CSERS process

WinterPark Engineering has helped many manufacturers try to understand how to implement CSERS for their unique vehicle applications. We have had many interesting discussions with CARB staff to understand the best approach for CSERS diagnostics.

Since so many OEMs are struggling to understand the requirements, CARB is proposing to make some changes to CSERS requirements to ensure consistent interpretation and implementation from all manufacturers.  For the past several years, CARB has been requesting manufactures provide a Federal Test Procedure (FTP) Bag1 (cold) vs Bag 3 (hot) comparisons of parameters known to be used to reduce cold start emissions.  This illustrates that components/elements used for catalyst heating can be identified.  Going forward, CARB is considering defining a metric, based on the integrated difference between FTP Bag 1 (cold) vs Bag 3 (cold), of a list of known components/elements used in CSERS strategies that can be used to identify what would be subject to CSERS monitoring.  If there is a significant difference in which the metric is large enough and therefore the cold vs hot conditions can be statistically separated, CSERS monitoring for that component/element would apply.

WinterPark focuses on keeping up with the changing CSERS regulations

WinterPark is following the CARB rulemaking process closely.  Once the updated regulation is released in early 2021, we will be up to speed and able to support manufacturers to ensure that their CSERS monitoring strategies meet the new requirements.  


California Air Resource Board. (2020) § 1968.2. Malfunction and Diagnostic System Requirements – 2004 And Subsequent Model-Year Passenger Cars, Light-Duty Trucks, and Medium-Duty Vehicles and Engines. Section 11.1.1. Thomson Reuters. https://govt.westlaw.com/calregs/Document/IE92473B8992248378C3C5ABA362FE285?transitionType=Default&contextData=%28sc.Default%29

California Air Resource Board. (2002) STAFF REPORT: INITIAL STATEMENT OF REASONS FOR PROPOSED RULEMAKING: Technical Status and Revisions to Malfunction and Diagnostic System Requirements for 2004 and Subsequent Model Year Passenger Cars, Light-Duty Trucks, and Medium-Duty Vehicles and Engines (OBD II). Page 24. https://ww3.arb.ca.gov/regact/obd02/isor.doc