Cummins fault code 1427
Overspeed Shutdown Relay Driver Diagnostic has detected an error: condition exists
What it means
Cummins' description: Overspeed Shutdown Relay Driver Diagnostic has detected an error - Condition Exists.
SPN 4185 is Overspeed Shutdown Relay Driver. FMI 31 means the ECM has confirmed the condition described in the code is happening.
These codes cover extra inputs and outputs the ECM controls or monitors: auxiliary temperature and pressure sensors, relays, lamps, and generator or equipment controls on off-highway and generator engines.
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
An auxiliary code for an accessory that isn't used on your truck.
Schedule a repair
An accessory, gauge or lamp not working with the code set. Fix the circuit when convenient.
Stop and get help
The code is tied to a shutdown or protection relay. Have it checked before relying on that protection.
Common causes
The sensor reading itself is out of range or the condition is real, so look at the system:
- Real reading from the equipment the input is monitoring
What you can check before calling
- Find out what the auxiliary input is wired to on your truck or equipment
- Check connectors and relays in that circuit
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, QSB 4.5, 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.
Related Auxiliary inputs, outputs and generator controls codes
- 1429 SPN 4187 FMI 31
High Engine Temperature (HET) Shutdown Relay Driver Diagnostic has detected an error: condition exists - 1432 SPN 4223 FMI 31
Pre-High Engine Temperature Warning Relay Driver Diagnostic has detected an error: condition exists - 1539 SPN 1387 FMI 3
Auxiliary Pressure Sensor Input 1 Circuit: circuit voltage high / shorted high - 1621 SPN 1387 FMI 4
Auxiliary Pressure Sensor Input 1 Circuit: circuit voltage low / shorted low - 779 SPN 703 FMI 11
Auxiliary Equipment Sensor Input # 3 (OEM Switch): root cause not known - 2194 SPN 1387 FMI 11
Auxiliary Equipment Sensor Input # 2 (OEM Pressure Sensor) Engine Protection: root cause not known
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 1427 mean?
Cummins fault code 1427 is J1939 SPN 4185 FMI 31: Overspeed Shutdown Relay Driver Diagnostic has detected an error - Condition Exists. In plain terms: overspeed shutdown relay driver diagnostic has detected an error: condition exists.
Can I keep driving with Cummins code 1427?
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 1427?
SPN 4185 identifies the part or system (Overspeed Shutdown Relay Driver). FMI 31 describes the type of failure: condition exists.
What usually causes Cummins code 1427?
The most common causes are: real reading from the equipment the input is monitoring.

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