310S Cheat Sheet 2026

The 30 highest-yield 310S facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. A musty odour from the HVAC vents when the A/C is first turned on is typically caused by: → Mould or bacterial growth on the evaporator core surface
2. During a cylinder leakage test, air is heard escaping from the tailpipe. What component is most likely at fault? → Exhaust valve
3. What causes cupping (scalloped wear) on tires? → Worn shock absorbers or struts allowing the tire to bounce and lose contact with the road
4. Before opening an A/C system component for replacement, the technician MUST: → Recover the refrigerant using certified recovery equipment
5. What does the manifold absolute pressure (MAP) sensor measure? → The pressure inside the intake manifold, which the ECM uses to calculate engine load
6. What is the purpose of the thermostat bypass circuit in an engine cooling system? → To circulate coolant within the engine block before the thermostat opens
7. A technician is checking camshaft endplay. Which measuring tool is most appropriate? → Dial indicator mounted to the block with the camshaft pushed fore and aft
8. An engine has low oil pressure at idle but normal pressure at higher RPM. What is the most likely cause? → Worn oil pump or excessive bearing clearances
9. What causes alternator whine in the audio system? → AC ripple from a failing rectifier diode coupling into the audio signal wiring
10. What condition does Plastigage measure? → Bearing oil clearance
11. A customer reports no heat despite the engine reaching normal operating temperature. Coolant level is correct. What should the technician check NEXT? → Heater core coolant flow and blend door actuator function
12. A vehicle equipped with daytime running lights (DRLs) has one DRL that does not illuminate. The headlights work normally. What is the most likely cause? → A burned-out DRL bulb or LED unit
13. A scan tool shows a P0300 diagnostic trouble code. What does this indicate? → Random or multiple cylinder misfire detected
14. Which vehicle system does the heater core draw its heat energy from? → The engine cooling system
15. A vehicle has a clunking noise from the front suspension when driving over bumps. What should be inspected first? → Stabilizer bar end links and bushings, ball joints, and strut mounts
16. When setting valve lash on an engine with solid lifters, what is the piston position for the cylinder being adjusted? → Top dead centre on the compression stroke
17. What is the correct procedure for performing a four-wheel alignment? → Adjust the rear alignment first, then align the front wheels to the rear thrust line
18. A vehicle has a P0420 code (catalyst system efficiency below threshold, bank 1). What is the most common cause? → A deteriorated catalytic converter that can no longer efficiently convert emissions
19. What is the primary cause of a lean misfire at idle? → An intake manifold vacuum leak allowing unmetered air to enter
20. What is indicated by a continuously fluctuating vacuum gauge reading at idle? → A worn camshaft lobe or weak valve spring
21. What is the purpose of the canister vent valve in the EVAP system? → To seal the charcoal canister from atmosphere during EVAP leak testing
22. What is the primary function of the condenser in an automotive A/C system? → To release heat from the refrigerant to the outside air
23. A multiplexed vehicle has total communication failure. Neither the scan tool nor any module responds. What should the technician check first? → The CAN bus terminating resistors and bus wiring for opens or shorts
24. A technician observes a downstream oxygen sensor signal that is flat at approximately 0.45 volts. What does this indicate? → The catalytic converter is functioning efficiently
25. What is the minimum acceptable brake pad thickness for most vehicles according to Canadian standards? → 2 mm (excluding backing plate)
26. What vacuum level should be achieved when evacuating an A/C system to ensure adequate moisture removal? → 500 microns (0.5 mm Hg) or lower
27. What does excessive blue smoke from the exhaust at startup indicate? → Worn valve stem seals allowing oil to seep into the cylinders
28. A technician observes that coolant is disappearing with no visible leaks. A combustion gas test of the radiator is positive. What is the diagnosis? → Internal head gasket leak allowing combustion gases into the cooling system
29. What is the purpose of the jounce bumper (bump stop) in the suspension system? → To prevent metal-to-metal contact when the suspension fully compresses
30. What causes a popping or snapping sound when turning the steering wheel at low speed? → A worn or dry upper strut mount bearing, CV joint, or ball joint