Cummins fault code 6569
SCR Outlet Temperature Sensor Circuit: circuit voltage high / shorted high
What it means
Cummins' description: Aftertreatment 1 SCR Outlet Temperature Sensor Circuit - Voltage above normal, or shorted to high source.
SPN 4363 is Aftertreatment 1 SCR Catalyst Outlet Gas Temperature. FMI 3 means the voltage on the circuit is higher than possible for a good sensor, usually an open signal wire, a short to a power wire, or a failed sensor.
The SCR (selective catalytic reduction) catalyst uses DEF to turn NOx into nitrogen and water. The ECM compares NOx before and after the catalyst to judge how well it's working. If it isn't, EPA rules require the engine to warn the driver and then derate.
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
A one-time code with no lamp, or the amber lamp clears after a few drive cycles and fresh DEF.
Schedule a repair
Amber lamp with SCR efficiency or NOx codes that keep returning. Schedule diagnosis. These usually get worse, and inducement timers can be running in the background.
Stop and get help
Blinking lamp, inducement countdown, or the engine is already derated to low power or 5 mph. Stop and get it diagnosed. Clearing codes alone won't reset a real inducement.
Common causes
FMI 3 is an electrical or signal fault, so start with the circuit:
- SCR temperature sensor or sensor module failed
- Wiring or connector damage at the catalyst
- NOx sensor reporting bad data
If the circuit checks out, the reading may be real. Other possibilities: bad or diluted DEF, or not enough DEF being dosed; crystallized or clogged DEF doser; failing NOx sensor (very common).
What you can check before calling
- Check DEF level and quality first. It's the cheapest fix
- Look for exhaust leaks or soot tracks at clamps ahead of the catalyst
- Write down any countdown or derate message on the dash before it changes
Clearing the code without fixing the cause usually brings it right back, and on emissions systems it can restart derate timers. For the bigger picture, read our guide: DEF warning lights and derate: what diesel drivers need to know.
Engines and sources
Listed by Cummins for: QSB 6.7, QSL 9, QSX 15, QSB 4.5, QSF 3.8 (With SCR). 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
- 3146 SPN 4363 FMI 3
SCR Outlet Temperature Sensor Circuit: circuit voltage high / shorted high - 3147 SPN 4363 FMI 4
SCR Outlet Temperature Sensor Circuit: circuit voltage low / shorted low - 3148 SPN 4363 FMI 2
SCR Outlet Temperature Sensor: erratic or intermittent signal - 3165 SPN 4363 FMI 0
SCR Outlet Temperature: reading above normal (most severe) - 3235 SPN 4363 FMI 16
SCR Outlet Temperature: reading above normal (moderately severe) - 6571 SPN 4363 FMI 4
SCR Outlet Temperature Sensor Circuit: circuit voltage low / shorted low
Related SCR catalyst and inducement codes
- 6597 SPN 6928 FMI 31
SCR System Cleaning Inhibited Due to System Timeout: condition exists - 6517 SPN 4364 FMI 17
SCR Catalyst Conversion Efficiency: reading below normal (least severe) - 6634 SPN 7848 FMI 14
SCR System Conditions Not Met for Active Cleaning: special instructions - 5654 SPN 6881 FMI 13
SCR Operator Inducement Override Switch: out of calibration - 5653 SPN 6881 FMI 9
SCR Operator Inducement Override Switch: abnormal update rate - 5632 SPN 6918 FMI 31
SCR System Cleaning Inhibited Due to Inhibit Switch: 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 6569 mean?
Cummins fault code 6569 is J1939 SPN 4363 FMI 3: Aftertreatment 1 SCR Outlet Temperature Sensor Circuit - Voltage above normal, or shorted to high source. In plain terms: scr outlet temperature sensor circuit: circuit voltage high / shorted high.
Can I keep driving with Cummins code 6569?
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 6569?
SPN 4363 identifies the part or system (Aftertreatment 1 SCR Catalyst Outlet Gas Temperature). FMI 3 describes the type of failure: circuit voltage high / shorted high.
What usually causes Cummins code 6569?
The most common causes are: sCR temperature sensor or sensor module failed; wiring or connector damage at the catalyst; nOx sensor reporting bad data.
Diesel down in the Midlands?
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