Cummins fault code 6525
Engine Oil Temperature Sensor 1 Circuit: circuit voltage low / shorted low
What it means
Cummins' description: Engine Oil Temperature Sensor 1 Circuit - Voltage below normal, or shorted to low source.
SPN 175 is Engine Oil Temperature 1. FMI 4 means the voltage on the circuit is lower than possible for a good sensor, usually a short to ground, a damaged harness, or a failed sensor.
The ECM monitors oil pressure, oil temperature and, on some engines, oil level. Low oil pressure is one of the fastest ways to destroy an engine, so Cummins treats it very seriously.
What the lamp means
This code normally doesn't turn on a dash lamp. It's logged in the ECM for a technician to see, and often explains another active code.
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 oil change reminder, or a sensor code where the gauge reads normal and the level is full.
Schedule a repair
Oil level low or a sensor code that keeps coming back. Top off and get it checked soon, and don't ignore oil consumption.
Stop and get help
Low oil pressure warning, gauge near zero, knocking, or a stop lamp. Shut the engine off immediately. Every second of low oil pressure damages bearings.
Common causes
FMI 4 is an electrical or signal fault, so start with the circuit:
- Oil pressure or temperature sensor failed
- Connector or wiring problem at the sensor
If the circuit checks out, the reading may be real. Other possibilities: low oil level; wrong oil viscosity or diluted oil (fuel or coolant in the oil); worn oil pump or bearings.
What you can check before calling
- Check the oil level with the engine off and level
- Look at the oil for milky color (coolant) or a fuel smell
- Note whether the oil gauge drops at hot idle
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, QSB 4.5, 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.
Same SPN, other failure types
- 212 SPN 175 FMI 3
Engine Oil Temperature Sensor 1 Circuit: circuit voltage high / shorted high - 213 SPN 175 FMI 4
Engine Oil Temperature Sensor 1 Circuit: circuit voltage low / shorted low - 214 SPN 175 FMI 0
Engine Oil Temperature: reading above normal (most severe) - 421 SPN 175 FMI 16
Engine Oil Temperature: reading above normal (moderately severe) - 425 SPN 175 FMI 2
Engine Oil Temperature: erratic or intermittent signal - 6524 SPN 175 FMI 3
Engine Oil Temperature Sensor 1 Circuit: circuit voltage high / shorted high
Related Engine oil codes
- 2155 SPN 611 FMI 4
Post-Filter Oil Pressure Sensor Circuit- Shorted Low: circuit voltage low / shorted low - 2154 SPN 611 FMI 3
Post-Filter Oil Pressure Sensor Circuit- Shorted high: circuit voltage high / shorted high - 1431 SPN 4188 FMI 31
Pre-Low Oil Pressure Warning Relay Driver Diagnostic has detected an error: condition exists - 1428 SPN 4186 FMI 31
Low Oil Pressure (LOP) Shutdown Relay Driver Diagnostic has detected an error: condition exists - 688 SPN 98 FMI 0
Engine Oil Level: reading above normal (most severe) - 649 SPN 1378 FMI 31
Engine Oil Change Interval: condition exists
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 6525 mean?
Cummins fault code 6525 is J1939 SPN 175 FMI 4: Engine Oil Temperature Sensor 1 Circuit - Voltage below normal, or shorted to low source. In plain terms: engine oil temperature sensor 1 circuit: circuit voltage low / shorted low.
Can I keep driving with Cummins code 6525?
Usually, yes. This code doesn't normally turn on a lamp by itself, but check for other active codes that might be more serious. Look at the green, yellow and red examples on this page to judge your situation.
What is the SPN and FMI for Cummins code 6525?
SPN 175 identifies the part or system (Engine Oil Temperature 1). FMI 4 describes the type of failure: circuit voltage low / shorted low.
What usually causes Cummins code 6525?
The most common causes are: oil pressure or temperature sensor failed; connector or wiring problem at the sensor.
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.