Automotive Service Technician

HEV safety: 600V+ high-voltage system; requires training, PPE (insulated gloves), documented isolation; arc hazard if careless. Safety regulations exist because the consequences of ignoring them are severe — injury, death, or legal liability. Know these requirements the way you know your own name.

P0420: downstream O2 sensor voltage not switching (catalytic converter not working); 80% are exhaust leaks, not converter failure. Understanding and applying code requirements correctly ensures your installations pass inspection and meet legal obligations in your jurisdiction.

Regen braking: saves energy; friction brakes mechanical backup; blended braking system (brake feel normal) managed by BCM. Troubleshooting is a systematic process: identify symptoms, narrow down causes logically, and verify your diagnosis before replacing parts. This logical approach is what examiners want to see.

EV HV safety: gloves rated for 600V+ (class 0/00), arc-rated coveralls, insulated tools; failure = life-threatening arc/shock. Memorize this formula and practise substituting values — exam questions often give you three variables and ask you to solve for the fourth.

Mode 6: manufacturer-specific test data; reveals sensor response range, circuit integrity; diagnostic potential without a code. Understanding and applying code requirements correctly ensures your installations pass inspection and meet legal obligations in your jurisdiction.

Immobilizer flash codes: 3 flashes = authentication failure; modern systems require reprogramming with factory scan tool. Understanding and applying code requirements correctly ensures your installations pass inspection and meet legal obligations in your jurisdiction.

Code maturity: 1st occurrence = pending; confirmed on next cycle = hard code; pending codes require 2-3 cycles to set, allowing intermittent issues. Understanding and applying code requirements correctly ensures your installations pass inspection and meet legal obligations in your jurisdiction.

Alternator output = f(rpm); low rpm = weak charging; test at 2000 rpm for rated output; low output indicates bearing drag or regulator fault. Memorize this formula and practise substituting values — exam questions often give you three variables and ask you to solve for the fourth.

Fuel trim: ECU adjusts injector pulse width based on O2 feedback; ±10% LTFT normal; ±15% suggests mechanical issue (vacuum leak, fuel pressure). Troubleshooting is a systematic process: identify symptoms, narrow down causes logically, and verify your diagnosis before replacing parts. This logical approach is what examiners want to see.

Soft codes: weather-dependent (cold soak O2 sensor lag); if hard code occurs again after clear, fault is repeatable = serious. Understanding and applying code requirements correctly ensures your installations pass inspection and meet legal obligations in your jurisdiction.

Limp mode: TCM detects fault (solenoid, sensor, pressure); limits gears to prevent clutch slip and heat damage; diagnostic = scan for DTC. Memorize this formula and practise substituting values — exam questions often give you three variables and ask you to solve for the fourth.

Random misfire (all cylinders): likely spark plugs, fuel pressure, or compression. Single cylinder: coil pack, plug wire, or fuel injector. Understanding and applying code requirements correctly ensures your installations pass inspection and meet legal obligations in your jurisdiction.

EVAP: traps refueling vapors in charcoal canister; purges to engine under load; EPA compliance; test pressure ~300 Pa (0.04 psi). Safety regulations exist because the consequences of ignoring them are severe — injury, death, or legal liability. Know these requirements the way you know your own name.

FPR: vacuum-referenced diaphragm adjusts spring tension; maintains 43-55 psi across injector regardless of engine load/rpm. Knowing what each component does — not just what it is — helps you diagnose failures, specify replacements, and explain your work to inspectors and clients.

Injector timing (PW) = f(load, rpm, O2, temp); ECU calculates from mass airflow; wider pulse = richer mixture = more power/emissions. Memorize this formula and practise substituting values — exam questions often give you three variables and ask you to solve for the fourth.

Freeze frame: ECU records rpm, load, temperature, fuel trim at moment code set; essential for understanding fault conditions. Understanding and applying code requirements correctly ensures your installations pass inspection and meet legal obligations in your jurisdiction.

Turbo boost + high CHT = detonation risk; modern engines reduce spark advance to prevent knock-induced damage to pistons. Memorize this formula and practise substituting values — exam questions often give you three variables and ask you to solve for the fourth.

Knock: destructive combustion; knock sensor detects vibration, triggers timing retard; persistent knock = fuel octane too low or engine carbon. Memorize this formula and practise substituting values — exam questions often give you three variables and ask you to solve for the fourth.

Lockup clutch: bypasses fluid coupling at steady-state; direct engine-to-trans ratio 1:1; reduces slippage heat/drag. Knowing what each component does — not just what it is — helps you diagnose failures, specify replacements, and explain your work to inspectors and clients.

Purge solenoid: energized during part-throttle operation (MAP > 5-10 kPa); richer mixture compensates for fuel vapors. Knowing what each component does — not just what it is — helps you diagnose failures, specify replacements, and explain your work to inspectors and clients.

Healthy O2 sensor: rapid voltage oscillation (poor fuel control = flat line, stuck high/low = sensor failed or electrical issue). Memorize this formula and practise substituting values — exam questions often give you three variables and ask you to solve for the fourth.

ADAS calibration: software verifies camera perceives lanes/objects correctly; miscalibration causes false alerts or missed hazards. Safety regulations exist because the consequences of ignoring them are severe — injury, death, or legal liability. Know these requirements the way you know your own name.

Active suspension monitoring: solenoid duty cycle, actuator response time; slow/no response = electrical fault or hydraulic failure. Memorize this formula and practise substituting values — exam questions often give you three variables and ask you to solve for the fourth.

Hot engine: thermostat failure (40%), radiator blockage (30%), water pump (20%), sensor (10%); thermostat is cheapest replacement. Troubleshooting is a systematic process: identify symptoms, narrow down causes logically, and verify your diagnosis before replacing parts. This logical approach is what examiners want to see.

ABS solenoid: cycles 5-10 times/second; reduces pressure to slip-controlled level; prevents skidding, maintaining steering control. Troubleshooting is a systematic process: identify symptoms, narrow down causes logically, and verify your diagnosis before replacing parts. This logical approach is what examiners want to see.

MAF (hot-wire): measures actual airflow; loss = rough idle. MAP (pressure): measures load; loss = no load information = hard start/hesitation. Memorize this formula and practise substituting values — exam questions often give you three variables and ask you to solve for the fourth.

Transmission wear metals: <50 ppm normal; 50-100 ppm increasing wear; >100 ppm critical; oil analysis tracks machine condition trend. On the job, a solid grasp of this concept means faster decisions, fewer errors, and work that passes inspection the first time.

Tire wear patterns: outer wear = under-inflation or positive camber; inner wear = toe-in or negative camber; diagnostic tool measures alignment. Memorize this formula and practise substituting values — exam questions often give you three variables and ask you to solve for the fourth.

Optimal slip: 10-15% allows steering + maximum braking; too much slip = longer stopping; 0% slip = lock-up, no steering. Memorize this formula and practise substituting values — exam questions often give you three variables and ask you to solve for the fourth.

Readiness monitors (O2, Cat, EGR, EVAP, etc.): vehicle runs self-tests during normal operation; 'not ready' = incomplete diagnostics/recent repairs. Memorize this formula and practise substituting values — exam questions often give you three variables and ask you to solve for the fourth.

BCM programming: window/lock positions, comfort settings relearned; critical for proper function after electrical work. Troubleshooting is a systematic process: identify symptoms, narrow down causes logically, and verify your diagnosis before replacing parts. This logical approach is what examiners want to see.