Exhaust Gas Recirculation (EGR) reduces NOx emissions by what mechanism, and what are common faults that impede EGR operation?

Exhaust Gas Recirculation (EGR) reduces NOx emissions by what mechanism, and what are common faults that impede EGR operation?

• A. EGR lowers combustion temperatures by recirculating a portion of exhaust gas back into the intake. Common faults: clogged passages, stuck EGR valve, faulty control solenoid/valve, vacuum leaks, or incorrect pressures.
• B. EGR increases combustion temperatures to improve power. Common faults: overcooling, excessive vacuum, and loose hoses.
• C. EGR has no effect on NOx; common faults are unrelated to emissions control.
• D. EGR reduces fuel economy by blocking exhaust gas entirely.

Answer: (A)