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Common Causes of Inspection Failure—Personal Vehicles

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

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.

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.

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.

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