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Common Causes of Inspection Failure—Commercial Vehicles

Gas Cap Inspection

Typical causes for failing a gas cap functional test:

  • Gas cap leaks.
  • Gas cap is non-removable or missing.

In most cases, simply replacing the old or missing gas cap with a new one will allow the vehicle to pass this portion of the test.

OBD Test

1996 and newer vehicles are tested by checking the vehicle OBD system (the vehicle’s computer) for problems. Causes for failing an OBD test:

  • The vehicle’s on-board diagnostic system reports a failure or problem with an emissions related component or sensor. If there is a problem, the “Check Engine” or “Service Engine Soon” light may be on. If the light is on when you come in for inspection, the vehicle will fail the test.
  • The Check Engine light is malfunctioning.
  • The diagnostic connector is missing, damaged, or not functioning.
  • During battery replacement or vehicle repair, the vehicle computer’s memory is reset.
  • If your vehicle has failed for being “not ready” and you have been operating your vehicle regularly, consult a repair technician before retest.

The VIR will provide specific reported trouble codes (up to 5 total when applicable) to further aid your mechanic in diagnosing and repairing the vehicles emissions systems.

Side Guards

The following will now be required for a commercial motor vehicle inspection exceeding gross vehicle weight rating (GVWR) 8,501 lbs:

Commercial motor vehicles based in the District with a manufacturer’s GVWR exceeding 8,501 lbs, but less than 26,000 lbs. GVWR shall be equipped with a side guard. If the side guards are not installed, or not installed properly, the vehicle fails safety inspection and cannot be registered in the District.

For more information, please visit the Side Guards webpage.

Tail Pipe Test

Typical causes for failing a tailpipe test include:

  • Air to fuel mixture may be incorrect.
  • Positive Crankcase Ventilation (PCV) valve may be malfunctioning or missing*
  • Vacuum leak present
  • Exhaust Gas Re-Circulation (EGR) may be malfunctioning*
  • Ignition timing may be incorrect
  • One or more worn, damaged, or fouled sparkplugs are present
  • Catalytic converter is clogged, missing, or ineffective*
  • Malfunctioning oxygen sensor
  • Internal engine parts may be malfunctioning or damaged
  • Dirty or contaminated engine oil
  • Clogged air filter

* Indicates items that may or may not be standard equipment

Vehicle Body

  • Damaged or rusted doors
  • Damaged and/or rusted quarter panel
  • Damaged and/or rusted hood
  • Damaged and/or rusted fenders
  • Damaged and/or missing bumpers
  • Damaged and/or missing bumper guards
  • Incorrect tag mounting
  • Missing or improper gas cap
  • Damaged body work

Vehicle Brakes

  • Worn or warped rotors
  • Damaged or worn front brakes
  • Damaged or worn rear brakes
  • Excessive brake noise
  • Leaking or damaged master cylinder
  • Leaking or damaged wheel cylinder
  • Damaged or non-operational vacuum booster
  • Non-operational parking brake
  • Non-operational brake warning light
  • Incorrectly adjusted pedal reserve
  • Missing and/or damaged pedal pads

Vehicle Documents and Miscellaneous Items

  • Missing or incorrect tags
  • Non-operational HVAC
  • Damaged or torn upholstery
  • Unacceptable sanitation
  • Damaged wheel chair
  • Damaged lift wheel
  • Incorrect tag mounting

Vehicle Exhaust

  • Leaking exhaust
  • Tampered exhaust
  • Missing or damaged exhaust converter
  • Loose exhaust
  • Flexible piping exhaust
  • Excessive exhaust noise
  • Excessive exhaust smoke
  • Excessive exhaust hydro carbon
  • Excessive exhaust carbon monoxide

Vehicle Glass

  • Cracked or damaged windshield
  • Cracked or damaged side window
  • Cracked or damaged rear window
  • Non-operational window controls
  • Unacceptable window tint
  • Missing or non-operational wipers
  • Missing or damaged wiper blades

Vehicle Lights

  • Non-operational signal lights
  • Non-operational backup lights
  • Non-operational tail lights
  • Non-operational stop lights
  • Non-operational tag lights
  • Non-operational clearance lights
  • Non-operational marker lights
  • Non-operational fog lights
  • Incorrect lens color
  • Damaged or missing side reflectors
  • Damaged or missing rear reflectors
  • Non-operational headlights
  • Non-operational indicator lights

Vehicle Safety

  • Missing or damaged mirrors
  • Missing or damaged horn
  • Missing or damaged seatbelts
  • Missing or damaged speedometer
  • Missing or damaged gear indicator
  • Missing or damaged safety chains
  • Missing or damaged chain guard

Vehicle Suspension

Damaged or unacceptable:

  • Kingpin
  • Shocks
  • Ball joints
  • Control arm
  • Rack and pinion
  • Tie rod ends
  • Idler arm
  • Pitman arm
  • Sleeve
  • Springs
  • Steering box
  • Steering wheel
  • Bearings
  • Steering linkage
  • Column
  • Alignment
  • Power steering
  • Bellows
  • CV joints

Vehicle Tires

  • Unacceptable or worn tire tread
  • Unacceptable or cut tire
  • Mixed tire types
  • Unacceptable knots and bulges in tires
  • Over- or under-inflated tires
  • Visible tire cord
  • Tire recap/tread front
  • Missing lug nuts

Visual Catalyst Inspection

All gasoline-powered vehicles 1975 and newer and less than 8501 lbs. gross vehicle weight will receive a visual catalyst inspection. Vehicles will fail the visual inspection if the catalyst is missing or has been tampered with. The catalyst must be repaired prior to re-inspection.



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