NAPA Cheat Sheet 2026

The 30 highest-yield NAPA facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. A fully charged lead-acid battery electrolyte at 80°F should have a specific gravity of about: → 1.265
2. A vehicle with a manual transmission will not crank unless the clutch pedal is depressed. Which component causes this? → Clutch pedal position (start) switch
3. During a four-wheel alignment on a vehicle with adjustable rear toe, which should be set first? → Rear toe, to establish the thrust line
4. With the A/C running, gauges show low-side pressure higher than normal and high-side pressure lower than normal. What is the most likely cause? → Worn or failing compressor
5. What does a large positive long-term fuel trim (LTFT) value indicate? → The ECM is adding fuel to compensate for a lean condition
6. A clicking noise is heard behind the dash when changing temperature settings. What is the most likely cause? → Stripped gears in a blend door actuator
7. On many modern vehicles, what replaces the mechanical proportioning valve? → Electronic brake force distribution (EBD) using the ABS modulator
8. What should you always do before lifting a vehicle? → Secure the lift points
9. Transmission fluid is dark brown and smells burnt. What does this usually indicate? → Overheated or burned friction material
10. What is the generally accepted maximum variation between the highest and lowest cylinder compression readings on a healthy engine? → About 10%
11. A crankshaft position sensor code sets only when the engine is hot, and the engine stalls. What is the best test approach? → Use a scope to monitor the CKP signal while heating the sensor
12. An upstream narrowband O2 sensor is stuck at about 0.1 volts while the engine runs. Which is the most likely cause? → Exhaust leak ahead of the sensor or a lean condition
13. Three resistors of 2, 4, and 6 ohms are connected in series across 12 V. What is the circuit current? → 1 A
14. A failed PCV valve stuck open would most likely cause which condition? → Lean idle and high idle speed
15. At idle, a vacuum gauge needle drops sharply by several inches at regular intervals. What is the most likely cause? → Burned or leaking valve
16. A stator one-way clutch that is seized (locked in both directions) typically causes what symptom? → Poor high-speed performance and fluid overheating
17. In a duo-servo drum brake, which shoe usually has the longer lining because it does most of the braking work? → The secondary (rear-facing) shoe
18. Fuel pressure is in spec at idle but drops well below spec under hard acceleration. What is the most likely cause? → Restricted fuel filter or weak pump
19. A cylinder shows 40 psi on a dry compression test and 45 psi on a wet test, while the other cylinders read 165 psi. What is the most likely cause? → Valve or head gasket leak
20. A system cools well for a while, then blows warm air, then cools again after being shut off. What is the most likely cause? → Moisture in the system freezing at the metering device
21. The manual valve in the valve body is positioned by which component? → The gear selector linkage or cable
22. A force of 100 lb is applied to a master cylinder piston with 1 sq in of area. What output force is produced at a caliper piston with 3 sq in of area? → 300 lb
23. When installing control arms with rubber bushings, when should the pivot bolts be torqued to final specification? → With the suspension at normal ride height
24. A secondary ignition oscilloscope pattern shows a very high firing line and a short spark line on one cylinder. What is the most likely cause? → Open or high-resistance plug wire or wide plug gap
25. A technician is performing a brake fluid flush. What is the primary reason for periodically replacing brake fluid? → The fluid is hygroscopic and absorbs moisture, lowering its boiling point.
26. Which tool is commonly used to diagnose electrical issues? → Multimeter
27. A spark plug with dry, black, sooty deposits most likely indicates what? → Rich mixture or weak spark
28. With the key on and engine off, a MAP sensor should read close to what value? → Barometric pressure
29. During a battery load test at 70°F, a load equal to half the CCA rating is applied for 15 seconds. The battery passes if voltage stays above: → 9.6 V
30. When bleeding the brakes on most non-ABS passenger vehicles, what is the generally accepted sequence? → Start with the wheel furthest from the master cylinder and work to the closest.