Three lanes are shut on the anti-clockwise carriageway between junction 28 for Brentwood, Essex, and junction 27 for the M11 near Epping. The HGV is broken-down with diesel seeping from the vehicle and onto the road.
Traffic is now queuing for up to six miles, with estimated travels times currently at around 90 minutes.
Queues have reached junction 29 for Upminster, reports Essex Live.
Clockwise traffic is also slow due to onlookers. Queues have reached junction 26 for Waltham Abbey and Copthall Green.
Images from motorway traffic cameras show bumper-to-bumper jams on the motorway, one of the busiest and most important roads in the UK.
Authorities suggest drivers use alternative routes, however these are also congested.
Some are leaving the motorway at junction 29 to use A127 west through Romford, and then local roads through Chigwell, Debden and Loughton to rejoin the M25 and junction 26.
But clockwise motorists are advised to stay on the M25 as traffic eases past the M11 link.
The M11 itself is slow southbound from the interchange with traffic struggling to join the anti-clockwise M25. Queues are back to junction 7 for Harlow.