Remove and replace light vehicle combustion engine units and components

Business Sectors (Suites): Maintenance and Repair - Light Vehicle
Developed by: IMI
Approved on: 30 Mar 2020


​This NOS is about removing and replacing units and components where dismantling and re-assembly of combustion engine systems is required. It is also about evaluating the performance of replaced units and components. The units and components concerned are not those replaced as part of normal routine, vehicle maintenance (servicing) activities.

Performance criteria

You must be able to:

P1 use suitable personal and vehicle protective equipment throughout all removal and replacement activities
P2 support your removal and replacement activities by reviewing

P2.1 vehicle technical data
P2.2 removal and replacement procedures
P2.3 legal requirements 
P3 prepare the vehicle systems and work area for safe working procedures as appropriate to the vehicle
P4 prepare, check and use all the equipment required following manufacturers' instructions
P5 carry out all removal and replacement activities following;

P5.1 manufacturers' instructions
P5.2 recognised repair methods
P5.3 health, safety and environmental requirements
P5.4 your workplace procedures
P6 work in a way which minimises the risk of:

P6.1 damage to other vehicle systems
P6.2 damage to other vehicle components and units
P6.3 contact with leakage
P6.4 contact with hazardous substances
P6.5 damage to your working environment
P7 ensure replacement combustion engine components and units conform to the vehicle operating specification and any legal requirements
P8 record and report any additional faults you notice during the course of your work promptly
P9 use suitable testing methods to evaluate the performance of the reassembled system accurately
P10 ensure the reassembled system performs to the vehicle operating specification and meets any legal requirements prior to return to the customer
P11 ensure your records are accurate, complete and passed to the relevant person(s) within the agreed timescale and in the format required
P12 complete all removal and replacement activities within the agreed timescale
P13 report any expected delays in completion to the relevant person(s) promptly

Knowledge and Understanding

You need to know and understand:

Legislative and organisational requirements and procedures
K1 the legal requirements relating to the vehicle
K2 the legislation and workplace procedures relevant to:

K2.1 health and safety
K2.2 the environment (including waste disposal)
K2.3 appropriate personal and vehicle protective equipment
K3 the importance of documenting removal and replacement information
K4 the importance of working to agreed timescales and keeping others informed progress
K5 the relationship between time and costs
K6 the importance of reporting anticipated delays to the relevant person(s) promptly

Use of technical information

K7 how to find, interpret and use sources of information applicable to units and component removal and replacement within combustion engine systems
K8 the importance of using the correct sources of technical information
K9 the purpose of and how to use identification codes

Electrical principles

K10 vehicle earthing principles and earthing methods 
K11 principles associated with vehicle combustion engine systems, including types of sensors, actuators, their application and operation
K12 types of circuit protection and why these are necessary
K13 electrical safety procedures 
K14 how warning circuits work
K15 electric symbols, units and terms
K16 battery charging
K17 electrical/electronic control system principles
K18 the hazards associated with working on or near high energy electrical vehicle components

Combustion engine system operation and construction *

K19 how *combustion engine systems and their related units and components are constructed, dismantled and reassembled for the classification of vehicle worked upon
K20 how combustion engine systems and their related units and components operate for the classification of vehicle worked upon


K21 how to prepare, check and use all the removal and replacement equipment required

Combustion engine unit and component removal and replacement

K22 how to remove and replace engine system mechanical and electrical unit components for the classification of vehicle worked upon
K23 how to select and fit gaskets, sealants, fittings and fasteners
K24 how to test and evaluate the performance of replacement engine units and components and the reassembled system against the vehicle operating specifications and any legal requirements
K25 the relationship between testing methods and the engine units and components replaced – the use of appropriate test methods
K26 the properties of jointing materials and when and where they should be used
K27 the manufacturer's specification for the type and quality of engine units and components to be used
K28 how to work safely avoiding damage to other vehicle systems, components units and contact with leakage and hazardous substances


**1.** **Equipment** is

1.1. hand tools
1.2. special workshop tools
1.3. general workshop equipment
1.4. electrical testing equipment

2. Testing methods are:

2.1. visual
2.2. aural
2.3. functional
2.4. measurement

3. Units and components are

3.1. mechanical
3.2. electrical

4. Combustion engine systems are

4.1. engine mechanical systems
4.2. cooling, heating and ventilation systems
4.3. air supply and exhaust systems
4.4. fuel and ignition systems
4.5. engine electrical systems
4.6. lubrication systems

Scope Performance

Scope Knowledge





This section contains examples and explanations of some of the terms used but does not form part of the standard.

Agreed timescales:
Examples include: manufacturer's recommended work times, job times set by your company or a job time agreed with a specific customer.

Units and components:
Any units or component from the engine system as defined in the Scope/Range above.

These can be any of the following – light vehicles, commercial vehicles, motorcycles, mopeds and scooters. Additionally, these vehicles may be SI, CI, Hybrid or Alternative fuel vehicles.

Alternative fuel:
This is defined as any type of fuel that may be used to power an internal combustion engine, examples would include LPG, bio ethanol etc.

Links To Other NOS

External Links

Version Number


Indicative Review Date

31 Mar 2024





Originating Organisation


Original URN


Relevant Occupations

Engineering, Light Vehicle Service Technician (Automotive), Vehicle Trades

SOC Code



Engine; combustion; units; components; light; remove; replace; oil; mechanical; electrical; cooling; lubrication