Cummins fault code 489
Transmission Output Shaft Speed: reading below normal (moderately severe)
What it means
Cummins' description: Transmission Output Shaft Speed - Data Valid But Below Normal Operating Range - Moderately Severe Level.
SPN 191 is Transmission Output Shaft Speed. FMI 18 means the value is clearly below normal operating range. It's the middle 'low' level.
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, QSX 15, QSF 3.8, QSG 12. 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.
- Older Cummins engines may report this code as SPN 191 FMI 1 (Transmission Output Shaft (Aux Gov) Speed Low – Warning).
Same SPN, other failure types
Related Accelerator pedal and driver controls codes
- 443 SPN 1043 FMI 4
Accelerator Pedal Position Sensor Supply Voltage Circuit: circuit voltage low / shorted low - 432 SPN 558 FMI 13
Accelerator Pedal or Lever Idle Validation Switch Circuit: out of calibration - 431 SPN 558 FMI 2
Accelerator Pedal or Lever Idle Validation Switch: erratic or intermittent signal - 551 SPN 558 FMI 4
Accelerator Pedal Idle Validation Circuit: circuit voltage low / shorted low - 387 SPN 1043 FMI 3
Accelerator Pedal Position Sensor Supply Voltage Circuit: circuit voltage high / shorted high - 287 SPN 91 FMI 19
SAE J1939 Multiplexing Accelerator Pedal Sensor System Error: network data error
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 489 mean?
Cummins fault code 489 is J1939 SPN 191 FMI 18: Transmission Output Shaft Speed - Data Valid But Below Normal Operating Range - Moderately Severe Level. In plain terms: transmission output shaft speed: reading below normal (moderately severe).
Can I keep driving with Cummins code 489?
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 489?
SPN 191 identifies the part or system (Transmission Output Shaft Speed). FMI 18 describes the type of failure: reading below normal (moderately severe).
What usually causes Cummins code 489?
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.