What to Do If an Old Car Fails the Annual Inspection?

[AdrianLynn]

If an old car fails the annual inspection, cleaning the three-way catalytic converter and the front oxygen sensor can improve the pass rate. Here are the detailed explanations: 1. Cleaning the three-way catalytic converter: The three-way catalytic converter is crucial for exhaust purification and is prone to carbon buildup, clogging, poisoning, or failure. Carbon buildup and clogging are reversible and can be restored by cleaning, while poisoning, failure, or damage require replacement. Use an OBD scanner to check all sensors. If no faults are found in the electronic control system, the issue is likely with the three-way catalytic converter. For cleaning, consider using oxalic acid solution. Remove the three-way catalytic converter, fill it with oxalic acid solution, and let it sit for half an hour. 2. Cleaning the front oxygen sensor: The front oxygen sensor plays a significant role in exhaust emissions. The oxygen sensor is often a 'hotspot' for carbon buildup. Carbon deposits from incomplete combustion in the engine can accumulate on the surface of the oxygen sensor, leading to sensor failure over time.