- What "Passing" Means for the H1 Exam
- The Cut Score: What Is and Isn't Verified
- How the H1 Is Built: 60 Questions, 50 Scored
- Turning Domain Weights into Question Counts
- Question Styles You Must Be Ready For
- A Scoring Strategy Built Around the Fuel System
- Logistics, Fees, and Retake Rules That Affect Your Score Plan
- Passing the Test vs. Earning the Certification
- Scheduling Domains Across Your Prep Weeks
- After You Pass: Validity and H1R Renewal
- Frequently Asked Questions
- ASE requires a passing result on H1, but no verified fixed cut score or percentage is published in official public sources.
- The H1 has 60 questions: 50 scored plus 10 unidentified unscored research questions, in 75 minutes.
- Fuel System Inspection, Diagnosis, and Repair carries 28% of scored questions, or 14 of the 50.
- Wait 30 full days after a pass or fail before purchasing and scheduling the same test again.
What "Passing" Means for the H1 Exam
The H1 is ASE's Compressed Natural Gas (CNG) Engines test, part of the Transit Bus Certification Tests series. It is computer-delivered, multiple choice, and has no hands-on practical component. Your result on that single computer-based test is what ASE uses to decide whether you have passed.
That sounds simple, and it is. But the question candidates ask most often, "what percentage do I need?", is exactly where a lot of online advice goes wrong. Before building any study plan around a target number, it helps to separate what ASE has actually published from what prep sites like to assert. If you are still orienting yourself on the credential itself, What Is H1 Certification? covers the basics.
The Cut Score: What Is and Isn't Verified
ASE states that a passing result on the test is required. What the official public sources reviewed for this article do not provide is an exact current H1 cut score or a fixed passing percentage. That gap is real, and it matters for how you prepare.
The practical consequence: do not aim for "just enough." Because you cannot see a verified target, the safest approach is broad competence across all eight domains, with extra depth where the question count is highest. A candidate who has a firm grasp of CNG fuel system diagnosis and solid general engine diagnosis has covered nearly half of the scored exam before touching anything else.
How the H1 Is Built: 60 Questions, 50 Scored
The H1 contains 60 questions in total. Of those, 50 are scored and 10 are unscored research questions. ASE does not identify which are which, so you must treat every question as though it counts.
| Element | Initial H1 | H1R (Recertification) |
|---|---|---|
| Total questions | 60 (50 scored + 10 unscored research) | 25, with no extra research questions |
| Time allowed | 75 minutes (1 hour 15 minutes) | 30 minutes |
| Format | Computer-delivered multiple choice, one correct answer | Computer-delivered multiple choice |
| Where taken | Prometric test center | Test center or Prometric ProProctor remote testing, subject to requirements |
Check-in, the tutorial, and the survey are not part of your 75 minutes; that time is additional. Still, the clock on the test itself is a genuine constraint. Seventy-five minutes across 60 questions leaves a little over a minute per question, which is comfortable for recall items but tighter for multi-step diagnostic scenarios. Flagging and returning to questions is supported, so you can move past a stubborn item and come back.
Turning Domain Weights into Question Counts
The eight content areas are officially weighted, and the published allocations total 50 scored questions and 100%. Because no fixed passing percentage is verified, the weights are your best planning tool. Here is how they translate.
| Domain | Weight |
|---|---|
| 1. General Engine Diagnosis | 18% |
| 2. Cylinder Head and Valve Train Diagnosis and Repair | 8% |
| 3. Engine Block Diagnosis, Repair, and Overhaul | 8% |
| 4. Lubrication and Cooling Systems Diagnosis and Repair | 8% |
| 5. Air Induction and Exhaust Systems Diagnosis and Repair | 14% |
| 6. Fuel System Inspection, Diagnosis, and Repair | 28% |
| 7. Starting and Charging System Diagnosis and Repair | 8% |
| 8. Ignition System Inspection Diagnosis, and Repair | 8% |
Fuel System Inspection, Diagnosis, and Repair is the largest at 28%, which is 14 of the 50 scored questions. General Engine Diagnosis follows at 18%, and Air Induction and Exhaust Systems Diagnosis and Repair is third at 14%. Together those three areas account for 60% of the scored exam. The remaining five domains are each 8%.
For a closer look at what each area expects, our companion piece H1 Exam Domains 2026: Complete Guide to All 8 Content Areas goes domain by domain.
Question Styles You Must Be Ready For
ASE's official samples for the Transit Bus tests show the question formats you will meet. Each has one correct answer, but the way the question is posed varies, and misreading the format is a classic way to lose points you actually know.
Diagnostic scenarios
A short description of a symptom or condition on a CNG-powered bus engine, followed by a question about the most likely cause or next step.
- Read the symptom, then the conditions, before looking at the options.
- Decide what you would check first in the shop; the answer often mirrors real diagnostic order.
Technician A / Technician B
Two technicians each make a statement. You judge whether A only, B only, both, or neither is correct.
- Evaluate each statement independently, as if the other did not exist.
- Watch for absolute words such as "always" and "never"; they frequently signal a flawed statement.
EXCEPT questions
Three options are true or applicable and one is not. You select the odd one out.
- Re-read the stem after choosing to confirm you answered the inverted question.
Diagram-based questions
An illustration, schematic, or figure accompanies the question and the answer depends on interpreting it.
- Trace the figure before reading the choices so the options do not bias your reading.
If you want a realistic sense of how these formats feel against the clock, working through questions on our H1 practice test site is a good way to build that fluency. ASE's own paid official practice test list does not include H1, so the official sample questions in the Transit Bus study guide are the authoritative reference for format.
A Scoring Strategy Built Around the Fuel System
Since the cut score is not published, think of your goal as maximizing correct answers where they are most plentiful. That points straight at Domain 6.
Mastering the 28% domain
Fuel System Inspection, Diagnosis, and Repair is not just the biggest domain; it is the one most specific to CNG. Candidates coming from diesel or gasoline backgrounds often underestimate it. Expect the questions to test your ability to inspect, diagnose, and repair the gaseous fuel delivery chain on a transit bus engine, including safe handling considerations unique to compressed natural gas.
Protecting the 18% and 14% domains
General Engine Diagnosis rewards methodical, symptom-driven reasoning, the same skill the diagnostic scenarios and Technician A/B items lean on. Air Induction and Exhaust Systems Diagnosis and Repair sits close to fuel delivery in a real engine, so studying them together reinforces both.
Key Takeaway
Do not spread study time evenly across all eight domains. Weight your hours roughly in proportion to the published allocations, then add a final pass over the five 8% domains so none becomes an easy-to-avoid blind spot.
Treat every question as scored
Ten of your 60 questions do not count, but you cannot tell which. Never "write off" a hard question as probably unscored. Answer everything, using flagging to manage time rather than to skip permanently.
Logistics, Fees, and Retake Rules That Affect Your Score Plan
Your preparation timeline interacts with ASE's scheduling rules, and those rules shape how much room you have for a second attempt.
- Purchase-to-test window: You must schedule and test within 90 days of purchase.
- Retake wait: After a pass or a fail, you must wait 30 full days before purchasing and scheduling the same test again.
- Cost per attempt: A single initial H1 attempt is a $62 test fee plus a $34 registration fee per order, totaling $96 before applicable tax. No member versus non-member price distinction is published.
- Multiple tests: A registration order can contain more than one test, which can be useful if you plan to test in more than one Transit Bus subject.
The full economics, including recertification caps, are laid out in H1 Certification Cost 2026: Complete Pricing Breakdown. The point for your score plan is simple: a failed attempt costs you both money and at least 30 days, so a thorough first attempt is the efficient path. For dates and deadlines in more detail, see H1 Exam Dates 2026: Testing Windows, Deadlines & Scheduling.
Test-day conditions
The initial H1 is taken at a secure Prometric test center; it is not an at-home exam. Scratch paper and pencils are supplied and must be returned, and the timer keeps running during an in-test break. Personal study materials and notes are restricted under test-center rules. ASE provides an English-to-Spanish technical glossary, and candidates for whom English is a second language may bring a standard published English-to-foreign-language dictionary under ASE language rules. Full Spanish test presentation is listed for other series, not the H-series.
Passing the Test vs. Earning the Certification
Here is a distinction many candidates miss: a passing score and an earned certification are not the same event. ASE certification requires two years of relevant full-time repair-technician experience, or the part-time equivalent. ASE permits specified education or training substitutions, but these require documentation for approval and cannot be stacked; ASE reviews the paperwork.
You may sit the H1 before you meet the experience requirement. If you pass, though, you cannot receive certification until that requirement is satisfied. There is no separate degree, mandatory prep course, prerequisite ASE exam, or professional-reference count specified. Our guide to H1 Requirements 2026: Eligibility, Prerequisites & How to Qualify walks through the documentation side.
Scheduling Domains Across Your Prep Weeks
Study methods matter less than where you aim them. Here is one way to sequence an eight-week plan around the H1's weighting, front-loading the highest-value domains so they get repeated review. For a broader walkthrough, see the H1 Study Guide 2026: How to Pass on Your First Attempt.
Fuel System first
- Domain 6: Fuel System Inspection, Diagnosis, and Repair, the 28% domain.
- Revisit it briefly at the end of week 4 and week 6.
Diagnosis foundation
- Domain 1: General Engine Diagnosis, practicing Technician A/B reasoning.
Air and exhaust
- Domain 5: Air Induction and Exhaust Systems Diagnosis and Repair, paired with fuel delivery concepts.
The 8% domains
- Domains 2, 3, 4, 7, and 8: Cylinder Head and Valve Train, Engine Block, Lubrication and Cooling, Starting and Charging, and Ignition.
Timed practice
- Full 60-question timed runs in 75 minutes, then targeted review of missed domains.
If you want a quick-reference companion while you work, the H1 Cheat Sheet 2026: One-Page Review of Must-Know Facts condenses the essentials. And since the exam's difficulty is a common worry, How Hard Is the H1 Exam? Complete Difficulty Guide 2026 offers context on what to expect.
After You Pass: Validity and H1R Renewal
An H1 certification is valid for five years. To renew, you pass H1R, a separate 25-question recertification test with no extra research questions and a 30-minute limit. Prometric ProProctor remote testing is available for H1 recertification, subject to remote-testing requirements. Previously certified candidates remain eligible for recertification even after expiry.
The public H-series renewal pathway is retesting; no CEU, CDU, or CPE quota is specified, and ASE's Renewal App is limited to its Automobile series and is not an H1 renewal route. Recertification test fees are capped at $186 per order plus the $34 registration fee, for a $220 maximum total before applicable tax.
Whether the credential pays off in your career is a separate question. The Is the H1 Certification Worth It? Complete ROI Analysis 2026 article and our H1 Salary Guide 2026: Complete Earnings Analysis cover that, and transit agencies and fleet maintenance operations running CNG buses are the natural employers to look to; see also H1 Jobs.
Frequently Asked Questions
ASE requires a passing result on the H1, but an exact current cut score or fixed passing percentage was not verified in the official public sources. Be cautious of any prep site that states a specific percentage as official H1 policy.
The initial H1 has 60 questions, of which 50 are scored and 10 are unidentified, unscored research questions. Because you cannot tell them apart, treat every question as if it counts.
Fuel System Inspection, Diagnosis, and Repair is the largest at 28%, equal to 14 of the 50 scored questions. General Engine Diagnosis at 18% and Air Induction and Exhaust Systems Diagnosis and Repair at 14% come next.
You must wait 30 full days after a pass or fail result before purchasing and scheduling the same test again. Each new initial attempt costs $62 plus a $34 registration fee, before tax.
Yes. Candidates may sit the H1 before meeting the experience requirement, but ASE will not award certification until two years of qualifying experience, or an approved documented substitution, is met.
For a deeper look at the credential's background, you can also read What Is H1?, and when you are ready to test your readiness against realistic questions, head back to the main H1 practice exam to start practicing.