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Elements and Performance Criteria

1. Identify and confirm the work requirement
   • Nature and objective of diagnosis requirements are determined from workplace instructions
   • Existence of fault in CNG fuel system is confirmed from direct or indirect evidence
   • Hazards associated with the work are identified and risks are managed according to workplace procedures, and safety and environmental requirements
2. Prepare to carry out diagnosis
   • Manufacturer specifications and other technical information for CNG fuel system are accessed and interpreted
   • Diagnostic procedures and options are identified
   • Diagnostic method sequence, tests and testing processes are selected from the range of available options
   • Testing equipment is selected and prepared according to manufacturer specifications and workplace procedures
   • Tools, equipment and materials required to support the diagnostic process are identified, selected and prepared for use
3. Apply diagnostic procedures
   • Selected diagnostic process is followed and testing is carried out according to manufacturer specifications, workplace procedures, and safety and environmental requirements
   • Diagnostic findings are confirmed, as required, by using reliable alternative or optional process according to manufacturer specifications and workplace procedures
   • Conclusions are drawn from findings and documented according to workplace procedures, including recommendations for necessary repairs that comply with AS/NZS 2739 Natural gas (NG) fuel systems for vehicle engines
   • Conclusions are provided to appropriate personnel or customer to confirm further action to be taken
4. Complete work processes
   • Vehicle or machinery is presented ready to be repaired or returned to the customer
   • Work area is cleaned, waste and non-recyclable materials are disposed of, and recyclable material is collected
   • Tools and equipment are checked and stored according to workplace procedures
5. Identify and confirm the work requirement
   • Nature and objective of diagnosis requirements are determined from workplace instructions
   • Existence of fault in CNG fuel system is confirmed from direct or indirect evidence
   • Hazards associated with the work are identified and risks are managed according to workplace procedures, and safety and environmental requirements
6. Prepare to carry out diagnosis
   • Manufacturer specifications and other technical information for CNG fuel system are accessed and interpreted
   • Diagnostic procedures and options are identified
   • Diagnostic method sequence, tests and testing processes are selected from the range of available options
   • Testing equipment is selected and prepared according to manufacturer specifications and workplace procedures
   • Tools, equipment and materials required to support the diagnostic process are identified, selected and prepared for use
7. Apply diagnostic procedures
   • Selected diagnostic process is followed and testing is carried out according to manufacturer specifications, workplace procedures, and safety and environmental requirements
   • Diagnostic findings are confirmed, as required, by using reliable alternative or optional process according to manufacturer specifications and workplace procedures
   • Conclusions are drawn from findings and documented according to workplace procedures, including recommendations for necessary repairs that comply with AS/NZS 2739 Natural gas (NG) fuel systems for vehicle engines
   • Conclusions are provided to appropriate personnel or customer to confirm further action to be taken
8. Complete work processes
   • Vehicle or machinery is presented ready to be repaired or returned to the customer
   • Work area is cleaned, waste and non-recyclable materials are disposed of, and recyclable material is collected
   • Tools and equipment are checked and stored according to workplace procedures

Range Statement

This section specifies work environments and conditions that may affect performance. Essential operating conditions that may be present (depending on the work situation, needs of the candidate, accessibility of the item, and local industry and regional contexts) are included. Bold italicised wording, if used in the performance criteria, is detailed below.

Safety and environmental requirements must include:

work health and safety (WHS) and occupational health and safety (OHS) requirements, including procedures for working with lighter-than-air flammable gas environmental requirements, including procedures for preventing loss of gas to atmosphere.

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Performance Evidence

Before competency can be determined, individuals must demonstrate they can perform the following according to the standards defined in this unit’s elements, performance criteria, range of conditions and foundation skills:

diagnose a complex fault in three different compressed natural gas (CNG) systems

the above diagnosis must involve two of the following types of complex faults:

an intermittent fault

a fault that affects more than one system

a fault introduced as a result of a system repair

an indirect fault caused by the influence of external systems.

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Knowledge Evidence

Individuals must be able to demonstrate knowledge of:

work health and safety (WHS) and occupational health and safety (OHS) requirements relating to diagnosing complex faults in CNG fuel systems, including procedures for working with lighter-than-air flammable gas

environmental requirements, including procedures for preventing loss of gas to atmosphere

types of complex faults relating to CNG fuel systems, including:

intermittent

multi-system

introduced as a result of system repair

indirect, caused by the influence of external systems

types, functions and operation of CNG fuel systems, including:

fuel lock-offs

injectors

mixers

metering units

requirements of AS/NZS 2739 Natural gas (NG) fuel systems for vehicle engines

testing procedures for CNG fuel systems, including:

component failure analysis

safety component operation

electrical control systems

exhaust emissions

on-road fuel efficiency

data interpretation

types, functions, operation and limitations of diagnostic testing equipment required to diagnose complex faults in CNG fuel systems

procedures for accessing and interpreting scan tool system data, including:

diagnostic trouble codes (DTCs), including:

conditions that set the DTCs

conditions for running DTCs

live data

freeze frame data

waveforms

vehicle continuous and non-continuous monitored systems

methods and processes for documenting and reporting diagnostic findings and recommendations.

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