Fault Codes

Volvo D13 Not Building Boost: Common Causes and What to Check First If your Volvo D13 is not building boost, […]

AC Throwing Hot Air? The 3 Most Likely Causes in Order The AC is on, the fan is blowing, but

Volvo D13 Headlights Not Working — Why a Fuse Won’t Fix It Headlights go out on a Volvo VNL with

Trailer Stop Lamps Not Working — Fuse, Relay, or Wiring? You hit the brakes and the trailer’s stop lamps don’t

Trailer Marker Lights Not Working — Where to Check First You walk around the trailer doing a pre-trip check and

Trailer Clearance Lights Not Working — What to Check on the Tractor The clearance lights — the lights along the

Trailer Turn Signal Lights Not Working — Diagnosis Starting Point You signal a turn, and the trailer’s signal lights don’t

DEF Gauge Stuck or Reading Wrong — Don’t Trust It Blindly Your DEF gauge shows a certain level — maybe

Truck Battery Keeps Dying Overnight — Finding the Drain You park with a healthy battery, and by morning it’s dead

DPF Won’t Complete Regen — What’s Stopping It Your truck is asking for a regen — either through a dash