1California  Air Resources  Board
Notice  of Effective  Dates  for Section  2196. 2 of the  
Heavy -Duty  Inspection  and Maintenance  Program  — 
California  Code  of Regulations  Title 13, Chapter  3.7, 
Sections  2195  through  2199.1
The California  Air Resources  Board  (CARB)  has established  an effective  date of April 1, 2024, 
for California  Code  of Regulations,  title 13, section  2196. 2 within  the Heavy -Duty Inspection  
and Maintenance  Regulation.
Background and Discussion
The Heavy -Duty Inspection  and Maintenance  (HD I/M) regulation1subjects  nearly  all 
non-gasoline  vehicles  with a gross  vehicle  weight  rating  over 14,000  pounds  that operate  in 
California  to periodic  emissions  testing.  These  testing  requirements  help ensure  that 
heavy -duty vehicles  operating  in California  remain  equipped  with properly  functioning  
emissions  controls,  and when  malfunctioning,  that these  systems  get repaired  in a timely  
manner.  Through  the repair  of malfunctioning  emissions  control  systems,  the HD I/M regulation  
will substantially  reduce  toxic particulate  matter  and emissions  of oxides  of nitrogen  from the 
heavy -duty vehicle  sector.  This will help reduce  air pollution  and improve  public  health  across  
the state,  especially  in communities  disproportionally  impacted  by heavy -duty vehicle  activity.
The HD I/M regulation  is being  implemented  through  a multi -phased  approach  with each  phase  
building  on the efforts  of the previous  one. In January  2023,  the regulation  began  the first 
implementation  phase  with deployments  of roadside  emissions  monitoring  equipment  to 
screen  for vehicles  operating  with potentially  high emissions.  Vehicles  identified  as potential  
high emitters  receive  a Notice  to Submit  to Testing  and are required  to submit  a passing  
compliance  test to CARB  within  30 days  of receipt  of the notice.
On September  22, 2023,  CARB  establish ed an effective  date of December  31, 2023 , for 
sections  2196.1 , subdivision  (f), 2196.8,  2197,  and 2197.2 , subdivision  (b), of the HD I/M 
regulation.  This announcement  mean t that owners  of vehicles  subject  to the HD I/M regulation  
must  report  their vehicles  to CARB  (§ 2197.2(b) ) and pay the annual  compliance  fee 
(§ 2196.1(f) ) by December  31, 2023.  Further,  the announcement  establishe d, through  
section  2197 , that freight  contractors,  brokers,  and applicable  freight  facilities  must  verify  that 
vehicles  they contract  with for services  or that enter  their facilities  are compliant  with the  
HD I/M regulation  as of December  31, 2023. Finally,  this announcement  establishe d that the 
parts  unavailability  compliance  time extension  provisions  of section  2196.8  are enacted  as of 
December  31, 2023,  to provide  vehicle  owners  a compliance  extension  mechanism  for 
situations  when  a repair  component  necessary  to bring  a vehicle  back  into compliance  is 
unavailable.
1Cal. Code  Regs.,  tit. 13, §§ 2195 -2199.12
Before  beginning  the implementation  of the final phase  of the program,  the HD I/M regulation  
requires  CARB  to notify  entities  of the effective  date through  publication  in the California  
Regulatory  Notice  Register  at least  90 days  prior to the effective  date.  Through  the publication  
of this notice,  CARB  is establishing  that the effective  date for section  2196.2  of the HD I/M 
regulation  is April 1, 2024.
As of April 1, 2024,  vehicles  subject  to the HD I/M regulation  must  pass  an emissions  
compliance  test twice  per year, except  motorhomes  and agricultural  vehicles , which  must  pass  
an emissions  compliance  test once  per year. Following  the initial  three  years  of periodic  testing  
requirements,  the compliance  testing  frequency  increases  to four times  per year on April 1, 
2027 , for vehicles  equipped  with onboard  diagnostics  systems.
For further  details  on these  enacted  regulatory  requirements,  refer to CARB’s  HD I/Mregulation  
webpage2.
California  Air Resources  Board
_________________________________
Steven  S. Cliff, Ph.D.,
Executive  Officer
Date:  December  18, 2023
The energy  challenge  facing  California  is real. Every  Californian  needs  to take immediate  
action  to reduce  energy  consumption.  For a list of simple  ways  you can reduce  demand  and 
cut your energy  costs,  seeCARB’s  website (www.arb.ca.gov).
2https://ww2.arb.ca.gov/our -work/programs/heavy -duty-inspection -and-maintenance -program