Our sales were very strong, up almost 9% as we saw the ongoing market strength continue from the second half of last year.
Sales in our Engine Management division were up more than 5%.
We inherited $12 to $14 million business with blue chip customers but almost more importantly, we acquired the intellectual property and complex manufacturing capabilities to court more business in this fast-growing product category, and new opportunities are already presenting themselves.
Overall, the OE channel accounted for over $150 million in sales last year and is the fastest-growing part of our business.
To begin, as you have seen in our release, our first-quarter gross margins in both segments reflected some of our best results in the last 10 years.
Fortunately, our global manufacturing footprint has been of benefit as compared to our peers sourcing 100% from Asia, recall our low-cost manufacturing facilities are in Mexico and Poland with other highly skilled and less labor-intensive operations in the US and Canada.
Looking first at the P&L, consolidated net sales in the first quarter were $276.6 million, up $22.3 million or 8.7% versus Q1 last year with increases coming from both of our segments.
Looking at it by segment,, Engine Management net sales in Q1, excluding wire and cable sales were $173.7 million, up $9.1 million versus the same quarter last year.
This 5.6% increase is partly reflective of the softness we experienced in Q1 last year but also reflects continued growth in sales with the ongoing customers that they are noted for.
Wire and cable net sales in Q1 were $38.4 million, up $1.8 million or 4.7%.
While the sales in the wire and cable business continued to be steady, the product category remains in secular decline, and we believe sales will ultimately resume a trend line of declines in the range of 6% to 8% on an annual basis.
Temperature Control net sales in Q1 2021 were $62.5 million, up 21.4% versus the first quarter last year and increased primarily as a result of stronger pre-season ordering by our customers.
Turning to gross margins, our consolidated gross margin in the first quarter was 30.3% versus 27.7% last year, up 2.6 points with both of our segments reporting increases for the quarter.
Looking at the segments, first-quarter gross margins for Engine Management was 30.7%, up 2.5 points from Q1 last year and for Temperature Control was 25.6%, an increase of 2.1 points from 23.5% last year.
While we expect the impact of higher sales and higher costs will have somewhat offsetting effects, gross margins will vary across quarters, and we continue to forecast full-year 2021 gross margin of 29% plus for this segment.
For our Temp Control segment, we continue to target a gross margin of 26% plus for the full year in 2021.
Moving now to SG&A expenses, our consolidated SG&A expenses in Q1 declined by $1.4 million to $54.5 million ending at 19.7% of sales versus 22% last year.
Looking at our SG&A cost for the full year in 2021, we expect expenses to be about $54 million to $58 million each quarter, a slightly higher range that noted on our last call as we'll see some higher expenses as a result of higher sales.
Consolidated operating income before restructuring and integration expenses and other income net in Q1 2021 was $29.3 million or 10.6% of net sales up 4.9 points from Q1 2020.
As we note on our GAAP to non-GAAP reconciliation of operating income, our performance resulted in first-quarter 2021 diluted earnings per share of $0.97 versus $0.43 last year.
Turning now to the balance sheet, accounts receivable at the end of the quarter were $174.1 million, up $21.9 million from March 2020, but down $23.9 million from December 2020.
Our inventory levels finished the quarter at $390.9 million, up $20 million from March 2020 reflecting the need to carry higher balances to support higher sales levels.
As compared to December 2020, our inventory was up $45.4 million, mainly due to our effort to restock our shelves to normal levels.
Looking at cash flows, our cash flow statement reflects cash used in operations in the first quarter of $11.4 million as compared to cash used of $32.8 million last year.
The $21.4 million improvement was driven by an increase in our operating income as noted earlier and by changes in working capital.
Turning to investments, we used $5 million of cash for capital expenditures during the quarter, which was slightly more than the $4.4 million we used last year.
We also used $2.1 million to purchase the SIP Sensor business from Stoneridge that was discussed earlier.
Financing activities included $5.6 million of dividends paid and $11.1 million paid for repurchases of our common stock.
Financing activities also included $31 million of borrowings on our revolving credit facilities, which were used to fund operations, investments in capital, and returns to shareholders through dividends and share buybacks.
We finished the quarter with total outstanding borrowings of $42.5 million and available capacity under our revolving credit facility $206 million.

Summary:
Looking first at the P&L, consolidated net sales in the first quarter were $276.6 million, up $22.3 million or 8.7% versus Q1 last year with increases coming from both of our segments.
As we note on our GAAP to non-GAAP reconciliation of operating income, our performance resulted in first-quarter 2021 diluted earnings per share of $0.97 versus $0.43 last year.