NVQ L4 Automobile Technician flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

COSHH assessment trigger

A COSHH assessment is required for any hazardous substance used or generated at work, and must be reviewed when the product, task, exposure or control measure changes.

WEL short-term limit

The 15-minute reference period exposure limit controlling peaks of exposure; it applies alongside the 8-hour time-weighted average and both must be complied with.

Class B fire

A fire involving flammable liquids such as petrol, solvents and paint. Extinguished with foam, CO2 or dry powder, never with a water jet that spreads the fuel.

Permanent diagnostic trouble code

A code stored in non-volatile memory that cannot be erased by a scan tool; it clears only after the ECU completes its self-test and confirms the fault is gone.

Freeze-frame data

A snapshot of engine operating conditions such as speed, load, temperature and fuel trim recorded at the instant a fault code was stored; key evidence for intermittent faults.

Voltage drop test

Measuring voltage lost across a conductor or connection while current flows. More than about 0.5 V on a power or ground circuit indicates excessive resistance.

Positive fuel trim meaning

The ECU is adding fuel to correct a lean condition, typically caused by an intake vacuum leak, low fuel pressure, a dirty mass airflow sensor or a leaking injector seal.

Cylinder leakage test

Compressed air is introduced into a cylinder at TDC; the escape path identifies the fault: intake valve, exhaust valve, crankcase rings or coolant passages.

Torque-to-yield bolt

A fastener tightened past its elastic limit into the plastic range, usually by a specified angle after a low torque figure; it must be replaced and never reused.

Wet compression test

A compression test repeated after adding oil to the cylinder. A significant rise indicates worn piston rings; no rise points to valves or head gasket.

CAN bus termination resistance

Two 120-ohm terminating resistors at each end of the bus give about 60 ohms measured across the CAN pair with the network powered down and modules asleep.

LIN bus characteristics

A single-wire, master-slave serial network typically running 9.6 to 20 kbit/s, used for low-speed body functions such as mirrors, seats and rain sensors.

High-voltage isolation test

A measurement of resistance between high-voltage conductors and chassis, compared against the manufacturer's minimum, performed with rated PPE and the system locked out.

Hall-effect sensor output

A three-wire sensor producing a digital square wave whose frequency or duty cycle varies with the measured quantity; it requires a supply, ground and signal circuit.

Disc thickness variation

Uneven disc thickness around the circumference, measured with a micrometer at several points; it causes brake pulsation because the caliper piston is pushed back and forth.

Toe angle wear pattern

Incorrect toe produces feathered wear across the tread, with one edge of each tread block worn more than the other; camber error instead gives one-sided shoulder wear.

ABS wheel speed sensor test

Check air gap and tone ring condition, then view the signal on an oscilloscope and compare amplitude and consistency across all four wheels while rotating.

Electronic parking brake service mode

A diagnostic routine that retracts the caliper motor so pads can be replaced; skipping it can damage the caliper piston, motor or gearbox.

Torque converter stall test

Full throttle applied with the brakes held in a drive range, comparing maximum engine speed to specification; high stall suggests slip, low stall suggests an engine or converter fault.

Outer CV joint failure symptom

A rhythmic clicking from the front wheel area during slow full-lock turns, caused by wear in the joint races; it worsens as wear progresses.

Driveline vibration isolation

Change gear at the same road speed: if vibration frequency tracks road speed it is wheels or propshaft; if it tracks engine speed it is clutch or flywheel.

Differential backlash

The small rotational clearance between ring and pinion teeth, set with shims and measured with a dial gauge; too little causes whine and heat, too much causes impact noise.

Legal tyre tread minimum

1.6 mm across the central three-quarters of the tread around the entire circumference for cars; cords or sidewall damage are also grounds for rejection.

Roller brake tester imbalance

The difference in braking force between the two wheels on the same axle, compared against a specified limit; excessive imbalance causes pull and instability under braking.

Calibration traceability

Measuring equipment must be calibrated within its interval and traceable to a national standard; an out-of-calibration instrument invalidates the recorded test result.

Diesel smoke opacity test

Free-acceleration test measuring exhaust smoke density against the limit for the vehicle's registration standard; it assesses combustion quality and injection condition.

Critical path in job planning

The longest sequence of dependent tasks that determines total job duration; delaying any task on it delays completion, while non-critical tasks carry float.

Supervised task allocation

Matching task complexity and risk to a technician's recorded competence; a less experienced technician works only under supervision appropriate to the risk.

Written handover record

A documented note of work completed, outstanding, parts fitted and safety-critical findings; verbal-only handover loses traceability and causes repeat work.

Quotation versus estimate

A quotation is a fixed price for defined work; an estimate is a prediction subject to change, so any additional work needs fresh customer authorisation before proceeding.

Complaint handling sequence

Listen fully, acknowledge the concern, establish facts, agree the remedy, confirm it in writing, then follow up to verify the customer is satisfied.

Unroadworthy vehicle notification

When a fault makes a vehicle unsafe to drive, the customer must be told clearly and in writing, and the advice recorded, before the vehicle is released.