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.