ADT Emissions Control & Environmental Compliance 2

Question 1

An Audi's NOx sensor reads abnormally high values after SCR catalyst replacement. What is the most likely cause?

Accepted Answer

Upstream NOx sensor measuring pre-catalyst exhaust

Answer

The upstream NOx sensor measures raw exhaust before the SCR, so high readings there are normal; the downstream sensor should show reduction.

Question 2

What EPA regulation requires Audi technicians to use refrigerant recovery equipment before servicing an A/C system?

Accepted Answer

Clean Air Act Section 608

Answer

Section 608 of the Clean Air Act mandates refrigerant recovery to prevent venting of ozone-depleting and greenhouse substances during stationary equipment service.

Question 3

A TFSI engine shows a P0299 (turbocharger underboost) code alongside elevated HC emissions. What component should be inspected first?

Accepted Answer

Charge air cooler for oil contamination

Answer

A leaking charge air cooler allows oil to enter the intake tract, raising HC emissions and reducing boost pressure simultaneously.

Question 4

Audi's Active Noise Cancellation system is unrelated to emissions, but which on-board system shares its CAN bus messaging to coordinate emissions reduction at high load?

Accepted Answer

Electrically controlled wastegate

Answer

The electrically controlled wastegate shares CAN data with the engine ECU to manage boost and combustion efficiency, directly influencing NOx and HC outputs.

Question 5

When performing a leak-down test on an Audi 2.0 TFSI, you find 25% leakage on cylinder 3 with air escaping into the crankcase. What is the emissions impact?

Accepted Answer

Elevated HC due to oil burning from blow-by

Answer

Blow-by past piston rings allows unburned fuel and combustion gases to enter the crankcase, increasing HC emissions when vented through the PCV system.

(ADT) Audi Diagnostic Technician Practice Test

(ADT) Audi Diagnostic Technician Practice Test

ADT Emissions Control & Environmental Compliance 2