Driver Guide

DEF Warning Light
What to Do First

Safe, general first steps. Truck down near Ocala or Wildwood? Call (352) 662-9996.

Safety First

Pull Over Safely

Get as far off the travel lanes as you safely can, or take the next exit if the truck can make it safely.
Turn on your hazard flashers right away.
Set out your three warning triangles as soon as you can, and within 10 minutes. On a divided road like I-75, federal rule 49 CFR 392.22 says one about 10 feet behind the truck on the traffic side, one about 100 feet back and one about 200 feet back.
Stay clear of traffic. If you are in danger, call 911. In Florida you can dial *FHP (*347) for the Highway Patrol.
Then call (352) 662-9996 with your exit or mile marker and what the truck is doing.

Sources: 49 CFR 392.22 (warning devices), Florida Highway Patrol, FL511 traffic. This is general safety info, not a repair manual. Follow your truck maker's manual and your company's rules.

Next Steps

If You Have a Def Warning Light Or Derate

Read the exact message on the dash. Write down any fault code and whether the truck says it will reduce power or speed.
Check the DEF gauge. A low DEF level is the simplest cause. Truck stops on this stretch sell DEF; Love's #708 lists 9 DEF lanes and Pilot #95 lists DEF lanes.
If the tank is full and the light stays on, it may be a sensor, heater, pump or wiring fault. That needs a mechanic with a scan tool.
Don't keep driving hard into a derate on a busy road. Pick a safe place to stop.

Call

Call for a Local Mechanic

Alligator Diesel is a 24/7 roadside diesel repair call line. We do not fix trucks ourselves. We connect you with a local partner shop or mobile mechanic, and the work depends on which shop is available.

☎ (352) 662-9996

Before You Call

What to Tell the Dispatcher

Where you are: road, mile marker, exit or truck stop
Truck and trailer type
What the truck is doing and any warning lights
If you are in a safe spot

Services

Related Services

DPF, DEF & Regen

Areas

Towns We Cover

Ocala, FL Wildwood, FL Belleview, FL The Villages, FL Leesburg, FL Bushnell, FL Reddick, FL Lake City, FL I-75 hub

Questions

Frequently Asked Questions

Will my truck shut down from a DEF warning?

Many newer diesels reduce power or speed if a DEF problem is not fixed. Your truck maker's manual explains what yours does. Call us before it gets that far.

Can a mobile mechanic fix a DEF problem on the roadside?

Often a mechanic can read codes and check the level, sensors and wiring where the truck sits. Some fixes need a part or a shop visit. The shop will tell you after hearing the codes.

What should I do first when my truck breaks down on the shoulder?

Turn on your hazard flashers and get as far off the travel lanes as you safely can. Federal rules (49 CFR 392.22) say to set out your warning triangles within 10 minutes. In Florida you can dial *FHP (*347) for help from the Highway Patrol. Then call us with your exit or mile marker.

Do you do the repairs yourselves?

No. Alligator Diesel connects your call with a local mobile diesel repair shop, and that shop does the work.

DEF Warning LightWhat to Do First