- What This Cheat Sheet Covers (and What It Doesn't)
- The Exam at a Glance
- Money and Booking Rules
- Experience and Eligibility Snapshot
- The Eight Content Areas, Ranked by Weight
- Question Styles You Will See
- The 28% Block: Fuel System Must-Knows
- Test-Day Rules in One Place
- Five-Year Validity and H1R
- A Weight-Driven Study Order
- Where the Credential Gets Used
- Quick FAQ
- H1 is ASE's Compressed Natural Gas (CNG) Engines test: 60 questions, 75 minutes, 50 scored plus 10 unscored research items.
- Fuel System Inspection, Diagnosis, and Repair carries 28% of scored questions, about 14 items, so it deserves the most study time.
- A single initial attempt costs $96: a $62 test fee plus a $34 registration charge, before tax.
- Certification lasts five years and renews by passing the 25-question, 30-minute H1R test.
What This Cheat Sheet Covers (and What It Doesn't)
This page is a compressed reference for the ASE Transit Bus series test known as H1: Compressed Natural Gas (CNG) Engines. It is meant for a final review pass: the numbers, rules, and content areas you should be able to recite without looking anything up. If you are still deciding whether to pursue the credential, start with What Is H1 Certification? and come back here once you are committed.
One caution up front. "H1" is shorthand shared by several unrelated credentials and programs. Everything below refers only to the ASE Transit Bus test for CNG engines, and every figure comes from ASE's public Transit Bus study guide (copyright 2026) and ASE's administrative pages. Where ASE does not publish a detail, such as an exact cut score, this sheet says so rather than guessing.
The Exam at a Glance
| Item | Initial H1 | H1R (Recertification) |
|---|---|---|
| Total questions | 60 (50 scored + 10 unscored research) | 25, no extra research questions |
| Time allowed | 75 minutes | 30 minutes |
| Format | Computer-delivered multiple choice, one correct answer | Computer-delivered multiple choice |
| Delivery | Prometric test center | Test center or Prometric ProProctor remote, subject to remote-testing requirements |
| Hands-on portion | None specified | None specified |
Check-in, the tutorial, and the survey are extra and do not come out of your 75 minutes. The 10 research questions are unidentified, so you cannot skip them or deprioritize them. Treat all 60 as if they count.
Money and Booking Rules
- Test fee: $62 per test.
- Registration fee: $34 per order, not per test. One order can hold more than one test.
- Single initial H1 attempt: $96 total before applicable tax.
- Recertification: same general-test fee schedule, with test fees capped at $186 per order plus the $34 registration, a $220 maximum before tax.
- Pricing tiers: no member versus non-member distinction is published.
- Scheduling window: you must schedule and test within 90 days of purchase.
- Retake wait: 30 full days after a pass or fail result before you can buy and schedule the same test again.
The registration fee being per order is the one detail worth planning around. If you intend to take more than one ASE test, bundling them in a single order avoids paying the $34 repeatedly. For the full breakdown, see H1 Certification Cost 2026: Complete Pricing Breakdown, and for calendar mechanics see H1 Exam Dates 2026: Testing Windows, Deadlines & Scheduling.
Experience and Eligibility Snapshot
ASE certification requires two years of relevant full-time repair-technician experience, or the part-time equivalent. ASE allows specified education or training substitutions, but they require documentation and ASE reviews it for approval. Those formal substitution alternatives cannot be stacked on top of each other.
What is not required: a degree, a mandatory H1 prep course, a prerequisite ASE exam, a universal training-hour count, or a number of professional references. You may take H1 before meeting the experience requirement, but you will not be certified until the requirement is satisfied. The full eligibility discussion lives in H1 Requirements 2026: Eligibility, Prerequisites & How to Qualify.
The Eight Content Areas, Ranked by Weight
ASE publishes eight weighted content areas totaling 100% and 50 scored questions. These are the official exam content areas, not editorial study modules.
| Rank | Content Area | Weight |
|---|---|---|
| 1 | Fuel System Inspection, Diagnosis, and Repair | 28% (14 scored questions) |
| 2 | General Engine Diagnosis | 18% |
| 3 | Air Induction and Exhaust Systems Diagnosis and Repair | 14% |
| 4 (tie) | Cylinder Head and Valve Train Diagnosis and Repair | 8% |
| 4 (tie) | Engine Block Diagnosis, Repair, and Overhaul | 8% |
| 4 (tie) | Lubrication and Cooling Systems Diagnosis and Repair | 8% |
| 4 (tie) | Starting and Charging System Diagnosis and Repair | 8% |
| 4 (tie) | Ignition System Inspection Diagnosis, and Repair | 8% |
Note the punctuation quirk: the weighting table writes the last area as "Ignition System Inspection Diagnosis, and Repair," while the task-list heading adds a comma after "Inspection." The content is the same either way.
The top three areas account for 60% of scored questions. The five 8% areas together make up the remaining 40%, which means no single one is large but collectively they are far from optional. A deeper walkthrough is in H1 Exam Domains 2026: Complete Guide to All 8 Content Areas.
Question Styles You Will See
All items are multiple choice with exactly one correct answer. ASE's official sample questions in the Transit Bus guide show four recurring patterns:
- Diagnostic scenarios: a symptom is described and you pick the most likely cause or best next step.
- Technician A / Technician B: two statements are made; you decide whether A, B, both, or neither is correct. Evaluate each statement independently before choosing.
- EXCEPT questions: three options are true and one is not. Reframe it as "find the false one" before you read the choices.
- Diagram-based questions: you interpret a figure, schematic, or component illustration.
Key Takeaway
On Technician A / Technician B items, judge each technician separately as true or false first, then map your two verdicts to the answer choices. Rushing to compare them is where most avoidable misses happen.
The 28% Block: Fuel System Must-Knows
Fuel System Inspection, Diagnosis, and Repair is the single heaviest area, and for a CNG engine it is also the area where the technology differs most from a gasoline or diesel bus. Expect questions that ask you to reason about how a gaseous-fuel system is built and how it fails.
Fuel System Inspection, Diagnosis, and Repair (28%)
Be able to trace fuel from storage to combustion and explain what each stage does and how a fault at that stage shows up as a symptom.
- High-pressure fuel storage and the safety devices associated with it
- Pressure regulation and the path from storage pressure down to engine supply pressure
- Fuel delivery components such as shutoff valves, filters, lines, fittings, and injectors or mixers
- Leak inspection and detection methods, and the safe-handling mindset around gaseous fuel
- Fuel-related diagnostic reasoning: driveability complaints, hard starting, power loss, and sensor or control inputs
The exact task list is on pages 5 through 8 of the ASE study guide, and it is the authoritative checklist. Use the cheat-sheet bullets above as prompts, then verify each against the official task list wording so you study what ASE actually tests rather than what a third party guessed.
Why this block rewards diagnostic thinking
With 14 scored questions here, a gap in fuel-system reasoning costs more than a gap anywhere else. Practice converting a symptom into a short list of candidate causes, then ruling them out in order of likelihood and ease of check. That is exactly what ASE's scenario-style items reward.
The supporting areas that feed it
General Engine Diagnosis (18%) overlaps heavily with fuel-system thinking because many complaints, such as misfire, rough running, and low power, begin as general diagnosis before pointing to fuel, air, or ignition. Air Induction and Exhaust Systems Diagnosis and Repair (14%) covers the air side of combustion, and Ignition System Inspection Diagnosis, and Repair (8%) matters because a spark-ignited gaseous-fuel engine depends on it. Studying these together makes the fuel block easier to reason about.
The Five 8% Areas
Individually small, collectively 40% of scored questions. Do not skip them.
- Cylinder Head and Valve Train Diagnosis and Repair
- Engine Block Diagnosis, Repair, and Overhaul
- Lubrication and Cooling Systems Diagnosis and Repair
- Starting and Charging System Diagnosis and Repair
- Ignition System Inspection Diagnosis, and Repair
Test-Day Rules in One Place
- Where: initial H1 is taken at a secure Prometric test center. It is not an at-home exam.
- Navigation: flagging questions and returning to them is supported.
- Scratch materials: scratch paper and pencils are supplied and must be returned.
- Breaks: the timer keeps running during an in-test break.
- Personal notes and study materials: restricted under test-center rules.
- Language support: ASE provides an English-to-Spanish technical glossary. 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 A1 through A9 and G1, not the H-series.
- Calculators and accommodations: no current H1-specific permission for a personal calculator was verified, so confirm directly with ASE and Prometric before test day.
Five-Year Validity and H1R
An H1 certification is valid for five years. You renew by passing H1R, a separate 25-question, 30-minute recertification test with no unscored research questions. Previously certified candidates remain eligible to recertify after expiration. The public H-series renewal pathway is retesting, and no CEU, CDU, or CPE quota is specified.
H1R can be remotely proctored through Prometric ProProctor, subject to ASE's remote-testing requirements. ASE's Renewal App is limited to its Automobile series and is not an H1 renewal route, so do not plan around it. Recertification fees follow the same general-test schedule, capped at $186 per order plus the $34 registration.
A Weight-Driven Study Order
If you have roughly a month, let the weights set your sequence. This is the only planning template in this sheet, and it exists to show where each content area belongs. For a fuller method, see H1 Study Guide 2026: How to Pass on Your First Attempt.
Fuel System Inspection, Diagnosis, and Repair
- Work the full 28% block against the official task list
- Practice symptom-to-cause reasoning on gaseous-fuel components
General Engine Diagnosis and Air Induction and Exhaust
- Cover the 18% and 14% areas back to back since complaints overlap
- Drill Technician A / Technician B and EXCEPT formats
The Five 8% Areas
- Valve train, block, lubrication and cooling, starting and charging, ignition
- Focus on diagram interpretation and failure symptoms
Timed Review
- Run timed mixed sets against the 75-minute limit
- Revisit your weakest content areas and the official sample questions
Because ASE's official paid-practice list does not include H1, the sample questions in the Transit Bus study guide are the only issuer-provided practice. Supplement them with a quality question bank, such as the H1 practice tests, and keep the official guide open as your reference for what is in scope.
Where the Credential Gets Used
H1 sits in ASE's Transit Bus series, so it is most relevant to technicians who maintain and repair CNG-powered buses. That generally points toward public transit agencies, municipal and regional fleets, school and contract bus operators running natural-gas vehicles, and independent shops that service heavy-duty natural-gas engines. The certification signals to an employer that you have demonstrated knowledge of this specific engine and fuel technology, which can matter when a fleet is converting to or expanding natural gas.
For employer-side detail, see H1 Jobs, and for the value question see Is the H1 Certification Worth It? Complete ROI Analysis 2026 and H1 Salary Guide 2026: Complete Earnings Analysis. This sheet deliberately avoids quoting wage or pass-rate figures, because ASE does not publish an H1-specific pass rate and individual provider claims do not establish one. For what the available evidence does and does not show, read H1 Pass Rate 2026: What the Data Shows. Likewise, ASE has not publicly confirmed an exact H1 cut score, so be wary of any site that states a fixed percentage; H1 Passing Score 2026: Exactly What You Need to Pass explains what is and isn't known. If you want a sense of the challenge, How Hard Is the H1 Exam? Complete Difficulty Guide 2026 covers it.
Quick FAQ
The initial H1 has 60 questions: 50 are scored and 10 are unidentified, unscored research questions. Because you can't tell which are which, answer every question carefully.
A single initial attempt is $96 before tax: a $62 test fee plus a $34 registration fee per order. The registration fee is charged per order, so multiple tests in one order share it.
Yes. ASE allows you to sit the test early, but you cannot receive certification until the two-year experience requirement, or an approved documented substitution, is met.
Start with Fuel System Inspection, Diagnosis, and Repair. At 28% of scored questions, about 14 items, it is the largest single area, followed by General Engine Diagnosis at 18% and Air Induction and Exhaust at 14%.
Pass H1R, the 25-question, 30-minute recertification test. It can be remotely proctored through Prometric ProProctor under ASE's remote-testing requirements. ASE's Renewal App does not apply to H-series tests.
That is the full one-page reference. If you want more context on the name and scope of the test, browse What Is H1? and H1 Training, and when you are ready to measure yourself against exam-style questions, start a timed run on the H1 Exam Prep practice tests.