ClearSign Technologies Corp

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To the Board of Directors and Stockholders of

ClearSign Technologies Corporation and Subsidiary

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheets of ClearSign Technologies Corporation and subsidiary (the "Company") as of December 31, 2024 and 2023, and the related consolidated statements of operations and comprehensive loss, stockholders’ equity, and cash flows for each of the two years in the period ended December 31, 2024, and the related notes (collectively referred to as the "consolidated financial statements"). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2024 and 2023, and the results of its operations and its cash flows for each of the two years in the period ended December 31, 2024, in conformity with accounting principles generally accepted in the United States of America.

Basis for Opinion

These consolidated financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on the Company's consolidated financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) ("PCAOB") and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the consolidated financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform an audit of its internal control over financial reporting. As part of our audits, we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company’s internal control over financial reporting. Accordingly, we express no such opinion.

Our audits included performing procedures to assess the risks of material misstatement of the consolidated financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the consolidated financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the consolidated financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matter

The critical audit matter communicated below is a matter arising from the current period audit of the consolidated financial statements that was communicated or required to be communicated to the audit committee and that: (1) relates to accounts or disclosures that are material to the consolidated financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of this critical audit matter does not alter in any way our opinion on the consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the account or disclosures to which it relates.

Carrying Cost of Patents and Other Intangible Assets

As described in Notes 2 and 4 to the consolidated financial statements, the Company’s patents and other intangible assets, net balance was $0.8 million as of December 31, 2024. The Company capitalizes third-party legal costs and filing fees, if any, associated with obtaining patents or other intangible assets. Once a patent asset has been placed in service, the Company amortizes these costs over the shorter of the asset’s legal or estimated economic life using the straight-line method. The Company also evaluates for potential impairment of long-lived assets, including intangible assets composed of patents, no less frequently than annually or whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable.

The principal considerations for our determination that performing procedures relating to the carrying value of intangible assets is a critical audit matter are the significant amount of judgment by management in developing the assumptions of future economic benefit in an impairment analysis, which in turn led to significant auditor judgment, subjectivity and effort in performing audit procedures and evaluating audit evidence relating to the analysis.

Addressing the matter involved performing procedures and evaluating audit evidence in connection with forming our overall opinion on the consolidated financial statements. These procedures included, among others, reviewing current and forecasted operating conditions for indication of impairment. We also reviewed board minutes, news, and industry reports for indications of impairment. Last, we obtained an understanding of potential future customers indicating future recoverability.

/s/BPM CPA LLP

We have served as the Company's auditor since 2011.

San Jose, California

March 31, 2025