AAR is running the process and agencies were contacted last week with a request for information.
Mother was appointed to Halfords’ advertising business in 2013, when it was worth £12m. The account was previously held by MullenLowe London (then DLKW Lowe).
Last year, Mother was tasked with devising Halfords’ new visual identity to grow brand love. The launch ad in June was a fast-paced family car journey to a campsite as told by a father.
It was part of the retailer’s "For life’s journeys" positioning.
Halfords marketing director Karen Bellairs said in June 2016 that, while the brand itself was well-recognised, consumer research had revealed that people knew less about its range of products and services. She said: "We’ve learned that consumers really know Halfords but, when we go a bit deeper, we start to see that they don’t really know why the brand exists."
In its 2016 financial report, Halfords reported a 1.7% rise in revenue to £1bn and 0.5% growth in underlying profit before tax to £81.5m.
A Halfords spokeswoman said: "We review all suppliers on a regular basis as standard practice to make sure they match the needs of our business.
"We have engaged AAR as an intermediary to look at our advertising agency relationships holistically and manage any resulting review process, which Mother will be invited to repitch on. Agencies invited to pitch will be informed directly."