P0720 — Output speed sensor circuit erratic
Seen on: Output shaft speed
Output speed sensor circuit erratic. Common causes: Sensor|Tone wheel|Air gap|Wire rub.
Your code rides along, so nearby mechanics see the fault before they quote you.
How serious is it?
Serious. Power derate likely — plan to stop soon.
Most likely causes
- Sensor
- Tone wheel
- Air gap
- Wire rub
First moves (roadside)
- Inspect sensor air gap
- Tone wheel condition
FAQ
Output speed sensor circuit erratic. Common causes: Sensor|Tone wheel|Air gap|Wire rub.
Serious — Power derate likely — plan to stop soon.
The most common cause is: Sensor. Other possibilities include Tone wheel; Air gap; Wire rub.
Power derate likely — plan to stop soon. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Find a mechanic or related guides
General diagnostic guidance for diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack and more). Not a substitute for a scan-tool diagnosis on your specific truck.