Please turn to Page 4 for a review of the key themes from our third quarter.
On a year-over-year basis, our volume and mix was down only 5% compared to a 20% decline in global light vehicle unit production.
Planning ahead, we have initiated new structural cost actions that will add to the $35 million benefit from the Accelerate+ program that are expected to carry over in 2022.
Our Performance Solutions segment is launching 34 BEV and hybrid programs expected to yield annualized revenues of $200 million.
Turning to Page 5.
Revenue was $4.3 billion, up 2% year-over-year, driven by our diversified end market mix and includes $1 billion of pass-through substrate sales.
Excluding substrates, our value add revenue was $3.3 billion, down 2% year-over-year, excluding the impact of foreign currency exchange rates.
As I highlighted on the previous page, this compares favorably to the industry light vehicle production decline of 20% and includes material cost recovery of $110 million.
In the third quarter, just over 50% of our business was generated from aftermarket and commercial truck off-highway and industrial applications.
Adding the light vehicle portion of our Performance Solutions business, which is agnostic to the vehicles powertrain, 65% of our value-add revenue is unrelated to OE light vehicle ICE technologies.
We expect this mix to expand to 80% plus by the end of the decade.
Adjusted EBITDA was $279 million and adjusted EBITDA margin was 8.5%.
Despite the volatile production environment, we maintained strong liquidity and our third quarter net leverage ratio improved 1.1 times since the end of 2020.
On Page 6, we show our enterprise performance.
We estimate the value-add revenue impact of the semiconductor shutdowns during the quarter was approximately $400 million and our most important geographies experienced the largest adjustment.
Also, our third quarter value-add revenues included $110 million of material cost recovery via price in the quarter, although no margin dollars came with that contribution.
On the right side of the page, adjusted EBITDA was $279 million at a value-add margin rate of 8.5%, down 330 basis points with almost half of the year-over-year margin rate decline due to temporary cost actions put in place last year that were not expected to repeat this quarter.
In the box on the right, you can see our Accelerate+ restructuring savings more than offset manufacturing inefficiencies associated with the supply chain shortages, which resulted in positive other operating performance of 60 basis points versus the prior year.
Let's turn to our motor parts business performance on Page 8.
Aftermarket revenue was $769 million, up 4% year-over-year on a constant currency basis on continued strong demand and relative to the second quarter, it is in line with normal seasonality.
Adjusted EBITDA for the quarter was $115 million, delivering a 15% EBITDA margin.
In addition, the late notice on OE customer production schedule changes, trapped inventory of approximately $250 million as of quarter end.
Let's turn to our Performance Solutions segment on Page 9.
Third quarter revenue was $686 million, down slightly year-over-year in constant currency.
Light vehicle applications, representing approximately two-thirds of the business, were down 10% excluding currency, outperforming industry production by 10 percentage points.
Commercial truck off-highway and other applications were up 58% year-over-year and made up almost 20% of revenues.
Adjusted EBITDA was $38 million in the third quarter for a margin of 5.5%.
Lastly, approximately 80% of our alternative propulsion launches in 2021 are battery electric vehicles.
On Page 10, we show Clean Air's results.
Clean Air value-add revenues were $897 million and fell 8% year-over-year, excluding foreign currency effects.
Light vehicle value-add revenues declined 22% year-over-year.
However, commercial truck off-highway and industrial value-add revenues increased 48% year-over-year.
Commercial truck off-highway and industrial comprised 27% of the segment's value-add revenues in the third quarter, compared to 19% for all of 2020.
Adjusted EBITDA was $137 million.
Value-add adjusted EBITDA margin was 15.3% compared to 15.6% in the prior year period.
Page 11 has a summary of Powertrain.
CTOHI and OE service revenues both expanded more than 20% year-over-year, which helped offset a 13% decrease in light vehicle revenues.
Adjusted EBITDA was $74 million and adjusted EBITDA margin was 7.9%.
I'll begin my comments on Page 13.
As of September 30th, our net leverage ratio was 3.2 times, which represented a 1.1 times improvement from our year-end ratio.
Our mid-term net leverage target range is 1.5 to 2 times.
We ended the quarter with strong liquidity of $2.1 billion with our revolver undrawn and no significant near-term debt maturities.
Page 14 shows our updated 2021 guidance.
We have revised our fiscal year 2021 value-added revenue guidance to a range of $13.55 billion to $13.65 billion, which compares to our prior range of $13.8 billion $14.1 billion.
Our guidance assumes Q4 global light vehicle production volumes of approximately 16.5 million units, flat with the third quarter, which is more conservative than IHS's most recent Q4 update.
We have reduced our 2021 adjusted EBITDA range from $1.25 billion to $1.28 billion from a range of $1.36 billion to $1.44 billion.
For the full year 2021, we continue to expect year-over-year savings of $110 million from our Accelerate+ Cost Reduction program.
We expect our net debt to improve to approximately $4.3 billion at year-end.
As Kevin mentioned, we estimate the trapped inventory approximately $250 million in the third quarter.
We have reduced our estimate for full year capex spend by $50 million due to the softer operating environment and our cash taxes are estimated to be approximately $140 million, $10 million lower than prior expectation.
Turning to Page 15.
We have identified and initiated new projects that we expect will contribute meaningfully in 2022 on top of the $35 million of carryover savings from Accelerate+.
In the mid-to-long term, we target a free cash flow to EBITDA ratio in the neighborhood of 25% to 30%.
On a go-forward basis, we believe the 65% of our revenue base, not associated with light vehicle IC applications, can outgrow the market and drive above market value-add revenue growth for the entire enterprise as the company transitions to a predominantly non-light vehicle IC revenue mix by the end of the decade.

Summary:
Revenue was $4.3 billion, up 2% year-over-year, driven by our diversified end market mix and includes $1 billion of pass-through substrate sales.
We have revised our fiscal year 2021 value-added revenue guidance to a range of $13.55 billion to $13.65 billion, which compares to our prior range of $13.8 billion $14.1 billion.
We have reduced our 2021 adjusted EBITDA range from $1.25 billion to $1.28 billion from a range of $1.36 billion to $1.44 billion.