The motorway is shut in both directions between junction 6 – Spaghetti Junction – and junction 7 for Great Barr, Birmingham, due to the blaze on the southbound carriageway. West Midlands Fire Service dashed to the scene at around 1pm and crews continue to fight the flames.
The southbound carriageway is most congested, with tailbacks to junction 9 for Walsall, West Midlands. Northbound traffic is back past junction 4a for the M42 and M6 Toll.
However, Birmingham Live reports alternative routes are busy too due to motorists diverting.
Southbound drivers are leaving at junction 7, and using the A34 south through the Great Barr and Perry Barr areas of Birmingham to go through the city centre.
Some northbound drivers are using the A452 from junction 5 to go through the Erdington and Sutton Coldfield areas to rejoin the motorway at junction 7 or further north at junction 9.
Traffic is also affected on the M5 northbound from junction 1 for West Bromwich, West Midlands, as queues tailback from the M6 link further north.
Transport for West Midlands said: “Delays of around 20 minutes on the M6 in both directions approaching J7 Great Barr, vehicle fire on the southbound carriageway, traffic was held in both directions.
“Additional traffic also likely through Perry Barr and Scott Arms [in Great Barr] with road users diverting, allow additional time.”