This page is for GM service technicians working toward MTC or World Class Technician status through GM Service Technical College. It sets out the verified rules: a score of 80% or better across performance-based exercises, results posted within 5 days, and a certification valid for 1 year with annual renewal. It also has free practice sets on engine, electrical, fuel and emissions, transmission, HVAC and ADAS topics, and worked explanations of our own questions.
Numbers in brackets link to the official sources listed under Sources & last verified. Dates that have passed are removed automatically.
| Item | Detail | Source · Verified |
|---|---|---|
| Passing score (Master Technician Certification (MTC)) | 80% or better[1] | General Motors / GM Service Technical College · Oct 29, 2026 |
| Validity (Master Technician Certification (MTC)) | 1 year[1] | General Motors / GM Service Technical College · Oct 29, 2026 |
| Renewal (Master Technician Certification (MTC)) | Annual renewal via maintaining STS requirements and ASE Certification[1] | General Motors / GM Service Technical College · Oct 29, 2026 |
| Delivery (Master Technician Certification (MTC)) | In-person performance-based evaluation at GM training locations[1] | General Motors / GM Service Technical College · Oct 29, 2026 |
| Eligibility (Master Technician Certification (MTC)) | 100% STS in Silver and Gold plus all MTC components[1] | General Motors / GM Service Technical College · Oct 29, 2026 |
| Eligibility (World Class Technician (current, through 2027)) | 8 of 9 Master Technician Certifications in Mechanical area plus matching ASE certifications[2] | gm-techlink.com · Oct 29, 2026 |
| Eligibility (World Class Technician (from 2028)) | 10 of 10 Master Certifications[2] | gm-techlink.com · Oct 29, 2026 |
| Score release (Master Technician Certification (MTC)) | Within 5 days[1] | General Motors / GM Service Technical College · Oct 29, 2026 |
According to General Motors / GM Service Technical College, “To successfully complete a Certification Event, the service technician must obtain a total score of 80% or better across the performance-based exercises.”[1]
The MTC is a GM certification for service technicians, run by GM Service Technical College (GM STC). It is not a written multiple-choice test. It is an in-person, performance-based evaluation held at training locations across the country, where you work through hands-on exercises.
Eligibility: to attain MTC, you must be 100% STS in both Silver and Gold and complete all MTC components.
Scoring and results: to complete a Certification Event, you need a total score of 80% or better across the performance-based exercises. The certifier posts your results on the Center of Learning within 5 days of the assessment.
Validity and renewal: GM STC recognizes the certification for 1 year, with annual renewal. You stay certified as long as you keep meeting your STS requirements for your area and keep your ASE Certification.
World Class Technician: under the current rules, which run through 2027, you reach WCT status by completing 8 of 9 MTCs in the Mechanical area along with the matching ASE certifications. Starting in 2028, the requirement becomes 10 of 10 certifications.
This page does not cover retake rules, fees, booking or session dates. Check the GM STC catalog at catalog.gmstc.com or ask your dealership training coordinator, because those details can change.
Prepare for the GM - General Motors Certified exam with our free practice test modules. Each quiz covers key topics to help you pass on your first try.
These are practice questions written for this site, not questions from the real exam. Each explanation shows why the right answer is right and why the others are wrong.
Question: What is the purpose of the Secondary Air Injection (AIR) system used on some GM engines during cold start?
Answer: B. Pump fresh air into the exhaust stream to oxidize unburned HC and CO during warm-up
Explanation:
B is correct. During a cold start the engine runs rich and the catalytic converter is not yet hot enough to work well, so the exhaust carries extra unburned hydrocarbons (HC) and carbon monoxide (CO). The AIR pump pushes fresh air into the exhaust stream. That adds oxygen, so those gases keep burning off and the converter warms up faster.
Rule to remember: AIR is an exhaust-side system that only works during warm-up. It adds oxygen after combustion to clean up HC and CO.
Question: How should ethical dilemmas be handled in Diagnostic Technology?
Answer: A. Follow established ethical guidelines, consult with supervisors, and prioritize stakeholder welfare
Explanation:
A is correct. Some diagnostic decisions involve honesty, safety or cost to the customer. In those cases, follow established professional and dealership guidelines, talk it through with a supervisor, and weigh the welfare of everyone affected: the customer, other road users and the business.
Rule to remember: on judgment questions, choose the answer that follows documented procedure, brings in the right people and protects safety.
Question: On a GM vehicle, what condition would cause the PCM to set a P0171 (System Too Lean, Bank 1) diagnostic trouble code?
Answer: B. A large vacuum leak causing unmetered air to enter the intake
Explanation:
B is correct. P0171 means the PCM has seen Bank 1 running lean and has added positive fuel trim until it hit its limit. A large vacuum leak lets air into the intake after the MAF sensor. The PCM never measures that air or adds fuel for it, so the mixture goes lean.
Rule to remember: lean codes point to unmetered air or too little fuel. Check for intake leaks first, then fuel delivery and MAF accuracy.
The MTC is hands-on, so use these practice sets to sharpen the theory behind the work you will do on the vehicle. They are not a copy of the assessment.
The parts, pre-owned, authorized service and dealer accreditation sets cover dealership programs, not technician skills. Use them only if your job involves those programs.
You need a total score of 80% or better across the performance-based exercises to complete a Certification Event. The score is for the event as a whole, not for each exercise on its own, so steady, accurate work on every exercise matters. For details on how individual exercises are weighted, check the GM STC catalog.
The certifier posts your results on the Center of Learning within 5 days of the assessment. If they have not appeared after that, ask your dealership training coordinator or contact GM STC through the channels listed in the official catalog.
GM STC recognizes the certification for 1 year, with annual renewal. You stay certified as long as you keep meeting your STS requirements for your area and keep your ASE Certification. If your STS status lapses in an area, check with GM STC on how that affects your certification.
To attain MTC, you must be 100% STS in both Silver and Gold and complete all MTC components. Confirm your status with your training coordinator before you book. GM STC sets the eligibility rules, so the official catalog has the current requirements.
Under the current rules, which run through 2027, you reach WCT status by completing 8 of 9 MTCs in the Mechanical area along with the matching ASE certifications. Starting in 2028, you will need 10 of 10 certifications. Check GM TechLink or GM STC for the full list of areas included.
No. It is an in-person, performance-based evaluation held at GM training locations across the country. The practice questions on this page are multiple choice and we wrote them ourselves. Use them to check the theory behind the hands-on tasks, not to predict what the assessment will look like.
How we verify: editorial & fact-checking policy. Report an error: contact us.