What to Do If the Vehicle Inspection Shows CO Non-Compliance?
3 Answers
If the CO (carbon monoxide) level is found to be non-compliant during the vehicle inspection, here are several solutions: 1. Replace the spark plugs. 2. Clean the contacts of the distributor and the distributor rotor. 3. Adjust the ignition timing. 4. Clean the air filter. 5. Use a cleaning agent to clean the throttle body. 6. Clean the three-way catalytic converter and the oxygen sensor. Additional Information: 1. Definition of Vehicle Inspection: The vehicle annual inspection process refers to the fixed procedure that motor vehicles must undergo each year for inspection. It is a mandatory test for every vehicle, equivalent to a physical examination for the vehicle, aimed at promptly eliminating potential safety hazards and reducing the occurrence of traffic accidents, commonly known as vehicle inspection. 2. Specific Process: The inspection includes checking the vehicle's appearance, exhaust emissions, brakes, lights, chassis, and the compulsory insurance documents, among other items.
Last year my car failed the annual inspection due to excessive CO emissions. I was quite worried about the exhaust issue the day before, but it got fixed later. Typically, CO exceeding standards indicates incomplete combustion, such as an overly rich air-fuel mixture or a faulty catalytic converter; common causes include a clogged air filter, carbon buildup on spark plugs, or a malfunctioning oxygen sensor. When I handled it myself, I first replaced the air filter, but that didn’t work. After inspection, I found severe carbon buildup in the catalytic converter—after cleaning it and running high-octane gasoline for a hundred kilometers on the highway, it passed the test. I suggest you start with the basics: check the filter and spark plugs, and if that doesn’t work, take it to a small shop for an OBD scan to read the error codes. Don’t ignore excessive emissions—prolonged driving could harm your health. Regular maintenance of the ignition and fuel systems can prevent such issues.
Excessive CO levels are commonly caused by catalytic converter or air-fuel ratio issues, which I've encountered frequently during my years of car modification. Specific causes include an overly rich fuel system, faulty O2 sensors, or aging three-way catalytic converters. When high CO is detected during emissions testing, these components should be investigated. For instance, incorrect air-fuel mixture can lead to incomplete combustion, and sometimes simply replacing the mass airflow sensor resolves the issue. For prevention, regular oil changes and filter replacements along with maintaining engine cleanliness help reduce emissions. For repairs, it's advisable to visit professional shops for diagnostics to avoid unnecessary part replacements. Before retesting, refuel with premium gasoline and drive extensively on highways to clean the exhaust system - this approach is cost-effective, efficient, and hassle-free.
