USPS Exams 943, 944, 945 (2025/2026) || 8 Pages of
Verified Correct Answers on Hydrocarbons, NOx &
Combustion
Description:
Updated USPS Exams 943, 944, and 945 study resource for 2025/2026. Includes 8 pages of
verified correct answers covering hydrocarbons, NOx emissions, combustion processes, and
related technical knowledge. Designed to ensure candidates pass USPS certification exams
with guaranteed success.
Keywords:
USPS exam 943 2025
USPS exam 944 verified answers
USPS exam 945 combustion test prep
USPS hydrocarbons and NOx exam
postal service technical exams 2026
Section 1: Hydrocarbons (HC) (25 Questions)
1. What are Hydrocarbons (HC) in the context of vehicle emissions?
A. Completely burned fuel vapor
B. Unburned or partially burned gasoline
C. A type of nitrogen compound
,D. The ash left after combustion
Answer: B
2. High levels of HC emissions are primarily caused by:
A. An engine running too hot
B. An overly efficient combustion process
C. An overly lean air/fuel mixture
D. Incomplete combustion
Answer: D
3. Which of these conditions would LEAST likely cause high HC emissions?
A. A rich air/fuel mixture
B. A misfiring spark plug
C. A faulty oxygen sensor
D. A perfectly functioning catalytic converter
Answer: D
4. A vacuum leak can cause high HC emissions because it leads to:
A. An overly rich mixture
B. An overly lean mixture that may not ignite properly
C. Increased cylinder temperatures
D. More complete combustion
Answer: B
5. What component is specifically designed to reduce HC emissions in the exhaust stream?
A. The muffler
, B. The catalytic converter
C. The exhaust manifold
D. The EGR valve
Answer: B
6. Which of these is a primary source of hydrocarbon evaporation emissions?
A. The tailpipe
B. The fuel tank and fuel lines
C. The exhaust manifold
D. The cooling system
Answer: B
7. HC emissions are measured in which of the following units?
A. Percent (%)
B. Parts per Million (PPM)
C. Volts (V)
D. Pounds per Square Inch (PSI)
Answer: B
8. A faulty ignition system (e.g., bad plug wires) can increase HC by causing:
A. Engine misfire
B. Overly rich fuel mixture
C. Low engine oil pressure
D. High coolant temperature
Answer: A
Verified Correct Answers on Hydrocarbons, NOx &
Combustion
Description:
Updated USPS Exams 943, 944, and 945 study resource for 2025/2026. Includes 8 pages of
verified correct answers covering hydrocarbons, NOx emissions, combustion processes, and
related technical knowledge. Designed to ensure candidates pass USPS certification exams
with guaranteed success.
Keywords:
USPS exam 943 2025
USPS exam 944 verified answers
USPS exam 945 combustion test prep
USPS hydrocarbons and NOx exam
postal service technical exams 2026
Section 1: Hydrocarbons (HC) (25 Questions)
1. What are Hydrocarbons (HC) in the context of vehicle emissions?
A. Completely burned fuel vapor
B. Unburned or partially burned gasoline
C. A type of nitrogen compound
,D. The ash left after combustion
Answer: B
2. High levels of HC emissions are primarily caused by:
A. An engine running too hot
B. An overly efficient combustion process
C. An overly lean air/fuel mixture
D. Incomplete combustion
Answer: D
3. Which of these conditions would LEAST likely cause high HC emissions?
A. A rich air/fuel mixture
B. A misfiring spark plug
C. A faulty oxygen sensor
D. A perfectly functioning catalytic converter
Answer: D
4. A vacuum leak can cause high HC emissions because it leads to:
A. An overly rich mixture
B. An overly lean mixture that may not ignite properly
C. Increased cylinder temperatures
D. More complete combustion
Answer: B
5. What component is specifically designed to reduce HC emissions in the exhaust stream?
A. The muffler
, B. The catalytic converter
C. The exhaust manifold
D. The EGR valve
Answer: B
6. Which of these is a primary source of hydrocarbon evaporation emissions?
A. The tailpipe
B. The fuel tank and fuel lines
C. The exhaust manifold
D. The cooling system
Answer: B
7. HC emissions are measured in which of the following units?
A. Percent (%)
B. Parts per Million (PPM)
C. Volts (V)
D. Pounds per Square Inch (PSI)
Answer: B
8. A faulty ignition system (e.g., bad plug wires) can increase HC by causing:
A. Engine misfire
B. Overly rich fuel mixture
C. Low engine oil pressure
D. High coolant temperature
Answer: A
