Cummins fault code 242
Wheel-Based Vehicle Speed Sensor Circuit tampering has been detected: abnormal rate of change
What it means
Cummins' description: Wheel-Based Vehicle Speed Sensor Circuit tampering has been detected - Abnormal rate of change.
SPN 84 is Wheel-Based Vehicle Speed. FMI 10 means the reading changed faster or slower than is physically possible, which points to a sensor or wiring problem, or a real sudden change.
The accelerator pedal has position sensors and an idle validation switch so the ECM knows exactly what the driver is asking for. Cruise control, brake and clutch switches, PTO and vehicle speed inputs are also monitored.
What the lamp means
An amber (yellow) warning lamp means the engine can usually keep running, but the fault should be repaired soon, ideally the same day.
Green, yellow, red: three ways this can look
The same code can be a quick fix or a reason to shut down. Match your situation to the closest example.
Keep an eye on it
A pedal or switch code that set once and cleared, and the pedal works normally.
Schedule a repair
Cruise doesn't work, the pedal feels dead in spots, or the code keeps returning. Have the pedal or switch checked.
Stop and get help
Engine stuck at idle or the pedal not responding, especially with a red lamp. Don't drive it in traffic. You won't have reliable throttle.
Common causes
The sensor reading itself is out of range or the condition is real, so look at the system:
- Pedal sensors disagreeing with each other
- Switch inputs that don't make sense together, like brake and throttle at once
What you can check before calling
- Check whether the engine stays at idle no matter what you do with the pedal
- Look at the pedal connector under the dash
- Check whether cruise control works
Clearing the code without fixing the cause usually brings it right back, and on emissions systems it can restart derate timers.
Engines and sources
Listed by Cummins for: QSB 6.7, QSL 9, QSF 3.8. Cummins uses the same fault code numbers across its electronic engines, including on-highway models like the ISB/B6.7, ISL/L9 and ISX/X15, though not every code applies to every engine or software level. Source: Cummins Tier 4 Fault Codes. Always confirm with Cummins service information (QuickServe) for your engine serial number.
Same SPN, other failure types
Related Accelerator pedal and driver controls codes
- 237 SPN 644 FMI 2
External Speed Command Input (Multiple Unit Synchronization): erratic or intermittent signal - 287 SPN 91 FMI 19
SAE J1939 Multiplexing Accelerator Pedal Sensor System Error: network data error - 194 SPN 520199 FMI 4
Cruise Control (Resistive) Signal Circuit: circuit voltage low / shorted low - 193 SPN 520199 FMI 3
Cruise Control (Resistive) Signal Circuit: circuit voltage high / shorted high - 148 SPN 91 FMI 0
Accelerator Pedal or Lever Position Sensor 1: reading above normal (most severe) - 147 SPN 91 FMI 1
Accelerator Pedal or Lever Position 1 Sensor Circuit Frequency: reading below normal (most severe)
Look up another code
Cummins fault code (like 1922), J1939 SPN and FMI (like SPN 3251 FMI 0), or an OBD-II code (like P0420).
Questions
What does Cummins fault code 242 mean?
Cummins fault code 242 is J1939 SPN 84 FMI 10: Wheel-Based Vehicle Speed Sensor Circuit tampering has been detected - Abnormal rate of change. In plain terms: wheel-based vehicle speed sensor circuit tampering has been detected: abnormal rate of change.
Can I keep driving with Cummins code 242?
Usually for a short time, if the engine runs normally and no other warnings are on. Get it diagnosed soon, because many amber codes lead to a derate if ignored. Look at the green, yellow and red examples on this page to judge your situation.
What is the SPN and FMI for Cummins code 242?
SPN 84 identifies the part or system (Wheel-Based Vehicle Speed). FMI 10 describes the type of failure: abnormal rate of change.
What usually causes Cummins code 242?
The most common causes are: pedal sensors disagreeing with each other; switch inputs that don't make sense together, like brake and throttle at once.
Diesel down in the Midlands?
We work on Cummins-powered pickups, vans and medium-duty trucks across Lexington, Columbia and the Midlands, on site at your yard or roadside.