The Municipal Ecology and Environment Bureau recently discovered during inspections that some heavy-duty diesel truck owners have tampered with their vehicle onboard diagnostic (OBD) systems, causing nitrogen oxide (NOx) emissions to exceed regulatory limits. This behavior is illegal, seriously harms air quality, and causes ongoing damage to the vehicles themselves.

Common methods of tampering with the vehicle onboard diagnostic (OBD) system include adding nuts to temperature sensors, installing OBD fault light shielding plugs, and using urea blockers. Unauthorized removal, deactivation, or modification of diesel truck after-treatment devices and tampering with the OBD system not only pollute the air but also harm the vehicles. Such violations are subject to hefty fines.

According to the Law of the People’s Republic of China on the Prevention and Control of Atmospheric Pollution, any act of falsifying vehicle emissions tests by temporarily replacing vehicle pollution control devices or tampering with the OBD system will result in corrective action orders from the environmental protection authorities at the county level or above. Vehicle owners will be fined 5,000 yuan per violation. Similarly, vehicle repair units found guilty of such misconduct will also be fined 5,000 yuan per vehicle.

Officials from the Municipal Ecology and Environment Bureau remind all vehicle owners:

Do not add nuts to temperature sensors.

Do not remove nitrogen oxide sensors and place them outside the vehicle.

Do not add diluted urea solution or liquid water.

Do not modify nitrogen oxide sensors or temperature sensors by relocating them to the tailpipe.

Do not insert portable shielding devices into the OBD port.

Do not bend the urea injection pipe to physically alter the flow rate.

Do not remove or damage exhaust purification devices such as DOC and DPF.

Do not install devices that adjust urea injection volume.

Vehicle owners who have engaged in these violations must immediately repair and rectify the issues. Meanwhile, environmental protection authorities will conduct random emission checks on heavy-duty diesel trucks.