Unit of competency details

AURHTZ3001 - Diagnose and repair heavy vehicle emission control systems (Release 1)


Usage recommendation:
Is superseded by and equivalent to AURHTZ001 - Diagnose and repair heavy vehicle emission control systems 13/Apr/2016
Supersedes AURT304666A - Repair and replace emission control systems 16/Jan/2013

Release Status:
ReleaseRelease date
1 1 (this release) 17/Jan/2013


SchemeCodeClassification value
ASCED Module/Unit of Competency Field of Education Identifier 030503 Vehicle Mechanics  

Classification history

SchemeCodeClassification valueStart dateEnd date
ASCED Module/Unit of Competency Field of Education Identifier 030503 Vehicle Mechanics  07/Aug/2013 
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Modification History



Release 1 

Replaces AURT304666A Repair and replace emission control systems

Performance Criteria, Range Statement and Critical Aspects of Evidence updated to reflect modern heavy vehicle technologies

Unit Descriptor

Unit descriptor 

This unit describes the performance outcomes required to diagnose and repair emission control systems fitted to heavy vehicles. It involves diagnosing deviations from correct operation, repair operations of emission control components and associated systems, and post-repair testing procedures.

Licencing, legislative, regulatory or certification requirements may apply to this unit in some jurisdictions. Users are advised to check with the relevant regulatory authority.

Application of the Unit

Application of the unit 

Work applies to the emission control systems of heavy vehicles in the road transport, mining, construction, agricultural and marine environments.

Licensing/Regulatory Information

Not applicable.


Not applicable.

Employability Skills Information

Employability skills 

This unit contains employability skills.

Elements and Performance Criteria Pre-Content

Elements describe the essential outcomes of a unit of competency.

Performance criteria describe the required performance needed to demonstrate achievement of the element. Where bold italicised text is used, further information is detailed in the required skills and knowledge and/or the range statement. Assessment of performance is to be consistent with the evidence guide.

Elements and Performance Criteria



1. Prepare to diagnose and repair a heavy vehicle emission control system

1.1. Workplace instructions  are used to determine job requirements 

1.2. Workplace health and safety (WHS) requirements  are observed and applied throughout the work

1.3. Procedures and information  are sourced and interpreted

1.4. National Environment Protection Measure for Diesel Vehicles (Guidelines) is sourced and observed throughout the work

1.5. Diagnosis options are analysed and those most appropriate to the circumstances are selected

1.6. Appropriate diagnostic tools and equipment are selected and prepared

2. Diagnose a heavy vehicle emission control system

2.1. Diagnostic tests  are performed according to workplace procedures and without causing damage to components or systems

2.2. Faults  are identified from diagnostic test results and causes of faults are determined

2.3. Diagnosis findings are reported according to workplace procedures, including recommendations for necessary repairs or adjustments

3. Repair a heavy vehicle emission control system

3.1. Repair options  are analysed and those most appropriate to the circumstances are selected

3.2. Appropriate tooling, techniques and materials are selected and prepared

3.3. Repairs and component replacements and adjustments are carried out without causing damage to components or systems and according to workplace procedures and manufacturer and component supplier specifications

3.4. Post-repair testing  is carried out according to workplace procedures and relevant legislation

4. Clean up work area and finalise work processes

4.1. Final inspection is made to ensure work is to workplace expectations and vehicle is presented ready for use

4.2. Tools and equipment are cleaned and stored according to workplace expectations

4.3. Workplace documentation is processed according to workplace procedures

Required Skills and Knowledge


This section describes the skills and knowledge required for this unit.

Required skills 

  • communication skills to:
  • clarify workplace instructions and determine job requirements
  • gain information from appropriate persons and assistance as required
  • initiative and enterprise skills to adapt to new and emerging situations in the workplace
  • learning skills to identify sources of information, assistance and expert knowledge to expand knowledge, skills and understanding
  • literacy skills to:
  • understand quality procedures
  • read and follow information on written job instructions, specifications, standard operating procedures, charts, lists, drawings and other applicable reference documents
  • obtain and record measurements
  • document repairs and parts required
  • numeracy skills to interpret instruments, gauges and other measuring equipment
  • planning and organising skills to:
  • plan own work requirements and prioritise actions to achieve required outcomes and ensure tasks are completed on time
  • identify risk factors and take action to minimise risk
  • problem-solving skills to:
  • determine the underlying causes of faults
  • recognise a workplace problem or a potential problem and take action
  • refer problems outside area of responsibility to appropriate person and suggest possible causes
  • seek information and assistance as required to solve problems
  • self-management skills to:
  • select and use appropriate equipment, materials, processes and procedures
  • recognise limitations and seek timely advice
  • teamwork skills to apply knowledge of own role to complete activities efficiently to support team activities and tasks
  • technical skills to use workplace tools relating to the repair of heavy vehicle emission control systems, including the use of:
  • specialised tools and equipment
  • measuring equipment
  • computerised technology
  • technology skills to:
  • operate diagnostic and test equipment
  • use technology to collect, analyse and provide information.

Required knowledge 

  • WHS regulations, requirements, equipment and material, and personal safety requirements relating to diagnosing and repairing heavy vehicle emission control systems
  • dangers of testing exhaust gases
  • legislation and regulatory requirements for heavy vehicle emissions
  • identification of motor vehicle emissions and their effects on the environment and health
  • application, purpose and operating principles of heavy vehicle emission control systems
  • identification of the effects of associated systems on vehicle emissions
  • interpretation of technical information, graphic symbols and diagrams
  • diagnostic and testing procedures for heavy vehicle emission control systems
  • repair procedures for heavy vehicle emission control systems
  • post-repair testing procedures of heavy vehicle emission control systems

Evidence Guide


The evidence guide provides advice on assessment and must be read in conjunction with the Performance Criteria, required Skills and Knowledge, the Range Statement and the Assessment Guidelines for the Training Package.

Overview of assessment 

Critical aspects for assessment and evidence required to demonstrate competency in this unit 

The evidence required to demonstrate competency in this unit must be relevant to workplace operations and satisfy all of the requirements of the performance criteria and required skills and knowledge.

A person who demonstrates competency in this unit must be able to:

  • observe safety procedures and requirements
  • select methods and techniques appropriate to the circumstances
  • complete preparatory activity in a systematic manner
  • diagnose and repair a range of heavy vehicle emission control systems relative to the qualification being sought
  • diagnose and repair heavy vehicle emission control systems according to workplace, manufacturer and component supplier requirements
  • present vehicle in a condition that complies with workplace requirements.

Context of, and specific resources for assessment 

Competency is to be assessed in the workplace or a simulated workplace environment that accurately reflects performance in a real workplace setting.

Assessment is to occur:

  • using standard workplace practices and procedures
  • following safety requirements
  • applying environmental constraints.

Assessment is to comply with relevant:

  • regulatory requirements
  • Australian standards
  • industry codes of practice.

The following resources must be made available for the assessment of this unit:

  • workplace location or simulated workplace
  • heavy vehicles with emission control faults relevant to the qualification being sought
  • equipment appropriate for the testing of heavy vehicle emission control systems
  • specifications and workplace instructions
  • tools appropriate for the repair, replacement and adjustment of heavy vehicle emission control systems.

Method of assessment 

Assessment must satisfy the endorsed Assessment Guidelines of this Training Package.

Assessment methods must confirm consistency and accuracy of performance (over time and in a range of workplace relevant contexts) together with the application of required skills and knowledge.

Assessment methods must be by direct observation of tasks and include questioning on required skills and knowledge to ensure correct interpretation and application.

Competence in this unit may be assessed in conjunction with other units which together form part of a holistic work role.

Where applicable, reasonable adjustment must be made to work environments and training situations to accommodate the needs of diverse clients.

Assessment processes and techniques must be culturally sensitive and appropriate to the language, literacy and numeracy capacity of the candidate and the work being performed.

Range Statement


The range statement relates to the unit of competency as a whole. It allows for different work environments and situations that may affect performance. Bold italicised wording, in the performance criteria, is detailed below. Essential operating conditions that may be present with training and assessment (depending on the work situation, needs of the candidate, accessibility of the item, and local industry and regional contexts) may also be included.

Workplace instructions  may include:

  • computer-generated instructions
  • verbal instructions
  • written instructions.

Job requirements  may include:

  • heavy vehicle emission control system diagnosis and repair methods, processes and equipment.

Workplace health and safety requirements : 

  • are those prescribed under legislation, regulations, codes of practice, and workplace policies and procedures
  • may include:
  • protective clothing and equipment
  • use of tools and equipment
  • handling of material
  • use of fire-fighting equipment
  • first aid equipment
  • hazard control, including control of hazardous materials and toxic substances.

Procedures and information  may include:

  • verbal, written and graphical instructions
  • signage
  • work schedules, plans and specifications
  • work bulletins or memos
  • material safety data sheets (MSDS)
  • diagrams or sketches
  • safe work procedures relating to the repair and replacement of heavy vehicle emission control systems
  • regulatory and legislative requirements relating to the automotive industry
  • National Environment Protection Measure for Diesel Vehicles (Guidelines)
  • Australian Design Rules
  • Engineer’s design specifications and instructions
  • organisational work specifications and requirements
  • instructions issued by authorised workplace or external persons
  • Australian standards
  • heavy vehicle service requirements and repair manuals.

Diagnostic tests  may include:

  • visual inspection of emission control system components
  • evaporative emission control
  • crankcase ventilation
  • exhaust gas recirculation
  • diesel exhaust fluid
  • catalytic converters
  • diesel particulate filters.

Faults  may include:

  • rough running
  • poor performance
  • excessive fuel consumption
  • excessive emissions (particulates, hydrocarbons, carbon monoxide, oxides of nitrogen)
  • excessive oil consumption.

Repair options  may include:

  • component repair procedures, including
  • removal, replacement and adjustment procedures
  • dismantle, repair, re-assembly and adjustment procedures.

Post-repair testing  may include:

  • exhaust gas colour assessment
  • exhaust gas composition analysis
  • on-board diagnostic system assessment procedures.

Unit Sector(s)

Competency field 

Mechanical – Heavy Vehicle

Unit sector 

Technical – Emission and Exhaust

Custom Content Section

Not applicable.