PSIP “Diesel Smoke Check”

Periodic Smoke Inspection Fleet Program or (PSIP) for short


3 Easy Need to Know about PSIP for Truckers

  • 1) Do diesel cars or trucks need to be smogged in CA?
  • 2) Whats the California Diesel “SMOG” Test Procedure?
  • 3) What happens if don’t pass diesel emissions?

1) Do diesel cars or trucks need to be smogged in CA?

Yes, Its now the law in California that it is required for all diesel trucks and diesel cars which are over 1997 year or newer must get an annual smoke check. Law states this test must be done by CCDET-Certified Technician.    

2)Whats the California Diesel “SMOG” Test Procedure?

Here are three steps emission inspection so you understand:

  • A) We visual inspect the engine and emission control equipment sometimes known as dpf, including (but not limited to) the EGR, PCV, DOC and SCR system. This checks for any problems or changes that are not compliant.
  • B) If customer requests it, we can do an (onboard diagnostics) inspection. This will see condition of the onboard computer. If any present diagnostic trouble codes (DTC) are in system we can tell you for identification of maintenance of truck.
  • C) Mechanic looks at tailpipe and crankcase before smoke test from the (smoke opacity test or “snap test”).
PSIP diesel smog test
Diesel smog test in Ventura county and Los Angeles county.

Actual Procedure of Diesel Smoke Test


A) First is the Idle Smoke Test.

We look at the tailpipe and we observe emissions with the truck idling for 10 seconds. We also look at crankcase for an extra 10 seconds while vehicle is still idling.    

B) BAR Snap Test –

The engine will be quickly accelerated between 2,000 – 3,000 rpm, this is the snap. Check to make sure no one is standing in front or behind vehicle before doing test. Look in mirror(s), mechanic will watch for excessive exhaust soot. This can also be do by second person if you cannot see. The throttle should be snapped 3 times. 3 second pauses between snaps which should be done, by put truck in neutral and then pushing foot on acceleration pedal down to floor. The first snap does not count towards the test. If any visible smoke that is spewed on the 1st snap will not counted of the full test. Large plumes of smoke that appear from the tailpipe and lingers for more than 3 second and 5ft-15 feet on the 2nd or 3rd snap will result in a failure of the test.  

3) What happens if don’t pass diesel emission test?

You must have each vehicle pass an annual smoke opacity test. The test machine has to be a SAE J1667 test procedure. Any vehicle that does not pass the test must be repaired. The truck must be re-tested after being fixed. We do not charge for a retest. Must met Standards of: 55% opacity for 1991 engines or earlier and 30% for 1991 and newer engines.  
Trucks Diesel smog test
Diesel smog near me is easy in Los Angeles with our mobil mechanic service