Exhibit 99.1

POWER SOLUTIONS INTERNATIONAL, INC. REPORTS FOURTH

QUARTER AND FULL YEAR 2012 RESULTS

Fourth quarter net sales up 15% year over year, 1% sequentially

Fourth quarter net income of $745,000 or $0.08 per diluted common share

Fourth quarter adjusted net income of $1,973,000 or $0.21 per diluted common share

Wood Dale, IL – February 28, 2013 - Power Solutions International, Inc. (OTC-BB: PSIX), a leader in the design, engineering and manufacture of emissions-certified alternative-fuel and conventional power systems, today announced its financial results for the fourth quarter and year ended December 31, 2012.

Fourth Quarter 2012 Results

Net sales for the fourth quarter of 2012 were $52,452,000, an increase of 15% from $45,489,000 in the fourth quarter of 2011, and a 1% increase from the third quarter of 2012. Sales in the quarter increased across most of the Company’s major end markets.

Operating income was $3,014,000, an increase of 16% from $2,599,000 in the fourth quarter of 2011, and a 5% increase from the third quarter of 2012. Operating margin of 5.7% was unchanged from the previous year, and up slightly from the third quarter of 2012. Operating income in the fourth quarter of 2012 includes costs of $206,000 related to the early termination of a lease. The Company terminated this lease as part of its previously announced facility consolidation. The after-tax impact of the early termination cost reduced net income by $124,000, or $0.01 per diluted common share.

Other expense for the fourth quarter includes a non-cash charge of $1,104,000 (or $0.12 per diluted common share) resulting from an increase in the estimated fair value of the liability associated with the warrants issued in the Company’s April 2011 private placement.

Net income for the fourth quarter of 2012, which includes the warrant revaluation adjustment and lease termination costs, was $745,000 or $0.08 per diluted common share. This compares to net income of $585,000 or $0.06 per diluted common share for the fourth quarter of 2011, which also includes a warrant revaluation adjustment. Net income for the fourth quarter of 2012

adjusted to remove the warrant revaluation impact and lease termination costs was $1,973,000 or $0.21 per diluted common share. This compares to adjusted net income for the fourth quarter of 2011 of $1,658,000 or $0.18 per diluted common share.

In addition to the impact of the warrant revaluation adjustment of $199,000 (or $0.02 per diluted common share), adjusted earnings per diluted common share for the third quarter of 2012 depicted in the table above includes an adjustment to remove costs of $303,000 ($182,000 after tax or $0.02 per diluted common share) incurred in connection with the relocation of the Company’s production, warehousing and administrative offices into new facilities. The fourth quarter of 2011 does not include any facility consolidation costs.

Full Year 2012 Results

Sales for 2012 were $202,342,000, an increase of 31%, from $154,969,000 for 2011. Net income for 2012 was $6,702,000 or $0.74 per diluted common share, compared to $4,061,000, or $0.44 per diluted common share for 2011. Adjusted net income for the year increased 68% to $7,455,000 or $0.81 per diluted common share compared to $4,443,000 or $0.48 per diluted common share year over year.

“We are pleased with both our fourth quarter and full year performance,” stated Gary Winemaster, Chairman and Chief Executive Officer of Power Solutions. “In a sluggish economy, we grew 2012 sales 31% and adjusted earnings per share 69% year over year. This outstanding growth, both top and bottom line, is a testament to the quality of our products, our strong customer relationships, and the size of the opportunity as industrial power systems transition from diesel to alternative fuels.”

Outlook

Power Solutions today provided its initial outlook for sales growth for 2013 and 2014. Sales in 2013 are targeted to be in a range of $225 to $235 million. Sales in 2014 are targeted to be in a range of $310 to $330 million.

This outlook reflects the Company’s current estimates based on a number of factors, including but not limited to the timing of new product ramps and the impact of global economic conditions on demand growth in its current markets. Please see the “Cautionary Note Regarding Forward-Looking Statements” below for additional risk factors.

Winemaster continued, “We are optimistic about our business prospects for 2013 and 2014, due to the initiatives we are taking to capture many exciting market opportunities. For instance, we expect our new 2.0L and 2.4L engines will gain strong acceptance in the forklift market, and

anticipate new customer wins this year that will provide significant revenue growth in 2014 and beyond. Furthermore, we believe our new 8.8L engine is an attractive offering for both off-road and ultimately on-road applications that will also contribute to growth in the years to come.”

Fourth Quarter and Full Year Earnings Results Conference Call

The Company will discuss its financial results and outlook in a conference call on February 28, 2013 at 3:30 PM CST. The call will be hosted by Gary Winemaster, Chief Executive Officer, Eric Cohen, Chief Operating Officer, and Daniel Gorey, Chief Financial Officer. Investors in the U.S. interested in participating in the live call should dial +1 (888) 428-9470. Those calling from outside the U.S. should dial +1 (719) 325-2396. Passcode 6349786 should be entered for both. A telephone replay will be available approximately two hours after the call concludes through March 14, 2013 by dialing from the U.S. +1 (877) 870-5176, or from international locations +1 (858) 384-5517, also entering passcode: 6349786. A simultaneous live webcast will be available on the Investor Relations section of the Company’s website at http://www.psiengines.com. The webcast will be archived on the Company’s website for one year.

About Power Solutions International, Inc.

Power Solutions International, Inc. (PSI) is a leader in the design, engineering and manufacture of emissions-certified, alternative-fuel power systems. PSI provides integrated turnkey solutions to leading global original equipment manufacturers in the industrial, off- and on-road markets. The company’s unique in-house design, prototyping, engineering and testing capacities allows PSI to customize clean, high-performance engines that run on a wide variety of fuels including natural gas, propane, biogas, diesel, gasoline, or hybrid systems.

PSI develops and delivers complete .97 to 22 liter power systems, including the new 8.8 liter engine aimed at the industrial and on-highway markets including; medium duty fleets, delivery trucks, school buses and garbage/refuse trucks. PSI power systems are currently used worldwide in power generators, forklifts, aerial lifts, and industrial sweepers, as well as in oil and gas, aircraft ground support, agricultural and construction equipment.

Cautionary Note Regarding Forward-Looking Statements

This press release contains forward-looking statements, including statements regarding the current expectations of Power Solutions International, Inc. (the “Company”) about its prospects and opportunities, including the statements under “Outlook.” The Company has tried to identify these forward looking statements by using words such as “expect,” “anticipate,” “estimate,” “plan,” “will,” “would,” “should,” “forecast,” “believe,” “guidance,” “projection” or similar expressions, but these words are not the exclusive means for identifying such statements. The Company cautions that a number of risks, uncertainties and other important factors could cause the Company’s actual results to differ materially from those expressed in, or implied by, the forward-looking statements, including, without limitation, the development of the market for alternative fuel power systems, technological and other risks relating to the Company’s development of its new 8.8 liter engine, introduction of other new products and entry into

on-road markets (including the risk that these initiatives may not be successful), the significant strain on our senior management team, support teams, manufacturing lines, information technology platforms and other resources resulting from rapid expansion of our operations, changes in environmental and regulatory policies, significant competition, global economic conditions (including their impact on demand growth) and the Company’s dependence on key suppliers. For a detailed discussion of factors that could affect the Company’s future operating results, please see the Company’s SEC filings, including the disclosures under “Risk Factors” and “Cautionary Note Regarding Forward-Looking Statements” in those filings. Except as expressly required by the federal securities laws, the Company undertakes no obligation to update or revise any forward-looking statements, whether as a result of new information, changed circumstances or future events or for any other reason.

Non-GAAP Financial Measures and Reconciliations

As used herein, “GAAP” refers to generally accepted accounting principles in the United States. The Company uses certain numerical measures in this press release which are or may be considered “Non-GAAP financial measures” under Regulation G. The Company has provided below for your reference supplemental financial disclosure for these measures, including the most directly comparable GAAP measures and associated reconciliations.

The Company believes supplementing its consolidated financial statements presented in accordance with GAAP with non-GAAP measures provides investors with useful information regarding the Company’s short-term and long-term trends. Adjusted net income and adjusted diluted earnings per common share are derived from GAAP results by excluding the non-cash impact related to the change in the estimated fair value of the liability associated with the warrants issued in the Company’s April 2011 private placement. The Company excludes this non-operating, non-cash impact, as the Company believes it is not indicative of its core operating results or future performance. The warrant revaluation results from facts and circumstances that

fluctuate in impact and is excluded by management in its forecast and evaluation of the Company’s operational performance. Adjusted net income and adjusted diluted earnings per common share also exclude costs incurred associated with the Company’s relocation of production, warehousing and administrative offices into new facilities. The Company excludes these costs as they, similar to the warrants, are not indicative of the Company’s core operating results or future performance and are excluded by management in its forecast and evaluation of the Company’s operational performance.

Adjusted net income, adjusted diluted earnings per common share and other non-GAAP financial measures used and presented by the Company may be calculated differently from, and therefore may not be comparable to, similarly titled measures used by other companies. Investors should consider non-GAAP measures in addition to, and not as a substitute for, or as superior to, financial performance measures prepared in accordance with GAAP.

Contact:

Power Solutions International, Inc.

Dan Gorey

Chief Financial Officer

+1 (630) 451-2290

dan.gorey@psiengines.com

ICR, LLC

Gary Dvorchak

Senior Vice President

+1 (310) 954-1123

gary.dvorchak@icrinc.com

Power Solutions International, Inc.

Condensed Consolidated Balance Sheets (Unaudited)

(Dollar amounts in thousands, except per share amount)

Power Solutions International, Inc.

Condensed Consolidated Statements of Operations (Unaudited)

(Dollar amounts in thousands, except per share amounts)

Power Solutions International, Inc.

Condensed Consolidated Statements of Cash Flows (Unaudited)

(Dollar amounts in thousands)