Exhaust EGR (Exhaust Gas Recirculation) Systems 2

Question 1

Which sensor is most commonly used to directly monitor EGR flow rate?

Accepted Answer

EGR differential pressure sensor

Answer

Mass air flow (MAF) sensor

Answer

Throttle position sensor (TPS)

Answer

Intake air temperature (IAT) sensor

Question 2

What OBD-II diagnostic trouble code most commonly indicates insufficient EGR flow?

Accepted Answer

P0401

Answer

P0300

Answer

P0420

Answer

P0171

Question 3

Under which operating condition does the PCM typically disable EGR flow completely?

Accepted Answer

Wide-open throttle (WOT) acceleration

Answer

Steady highway cruising

Answer

Light city stop-and-go driving

Answer

Moderate uphill climbing at partial throttle

Question 4

In a high-pressure EGR system, where is exhaust gas extracted from?

Accepted Answer

Upstream of the turbocharger turbine inlet

Answer

After the diesel particulate filter (DPF)

Answer

After the catalytic converter outlet

Answer

From the crankcase ventilation circuit

Question 5

What condition typically results from EGR cooler failure?

Accepted Answer

Coolant contamination of the intake and white smoke from exhaust

Answer

Increased NOx emissions with no other symptoms

Answer

Improved fuel efficiency due to cooler intake temperatures

Answer

Reduced exhaust backpressure and increased power

Question 6

What is the most likely symptom of an EGR valve stuck in the closed (non-flowing) position?

Accepted Answer

Elevated NOx emissions with minimal driveability symptoms

Answer

Rough idle and frequent misfires

Answer

Engine overheating at idle speed

Answer

Excessive black smoke from exhaust

Question 7

What material is most commonly used for EGR cooler cores due to resistance to exhaust heat and corrosion?

Accepted Answer

Stainless steel

Answer

Aluminum

Answer

Cast iron

Answer

Copper-brass alloy