Cummins fault code 3156
Warm Up DOC Outlet Temperature Sensor Circuit: circuit voltage low / shorted low
What it means
Cummins' description: Aftertreatment Warm Up Diesel Oxidation Catalyst Outlet Temperature Sensor Circuit - Voltage below normal.
SPN 4810 is Aftertreatment Warm Up Diesel Oxidation Catalyst Outlet Temperature. 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 DOC (diesel oxidation catalyst) sits ahead of the DPF and burns fuel and hydrocarbons to heat the exhaust for regeneration. Some engines have a separate aftertreatment fuel doser (the 7th injector) that sprays fuel into the exhaust for regen.
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 temperature sensor code that appears once and clears, with regens finishing normally.
Schedule a repair
Regens failing or taking much longer than usual, along with DOC or doser codes. Book diagnosis before the DPF loads up.
Stop and get help
Raw fuel smell, smoke out of the stack, or a stop lamp. Don't run it. Unburned fuel in the exhaust is a fire risk and can destroy the DPF.
Common causes
FMI 4 is an electrical or signal fault, so start with the circuit:
- Temperature sensor or sensor module failed
- Aftertreatment fuel doser, shutoff valve or pressure sensor wiring fault
- Connector heat damage
If the circuit checks out, the reading may be real. Other possibilities: aftertreatment fuel injector clogged or coked up; dOC face-plugged with soot or oil; dOC catalyst worn out or contaminated.
What you can check before calling
- Look for soot or fuel residue at the aftertreatment fuel doser and lines
- Check for exhaust leaks between the turbo and the DOC
- Note whether regens are completing or being interrupted
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: DPF regeneration explained: passive, active and forced.
Engines and sources
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
- 3155 SPN 4810 FMI 3
Warm Up DOC Outlet Temperature Sensor Circuit: circuit voltage high / shorted high - 3157 SPN 4810 FMI 2
Warm Up DOC Outlet Temperature: erratic or intermittent signal - 3162 SPN 4810 FMI 0
Warm Up DOC Outlet Temperature: reading above normal (most severe) - 3169 SPN 4810 FMI 16
Warm Up DOC Outlet Temperature: reading above normal (moderately severe) - 3249 SPN 4810 FMI 15
Warm Up DOC Outlet Temperature: reading above normal (least severe)
Related DOC and aftertreatment fuel doser codes
- 3154 SPN 4809 FMI 2
Warm Up DOC Intake Temperature: erratic or intermittent signal - 3158 SPN 4793 FMI 31
Warm Up DOC Missing: condition exists - 3153 SPN 4809 FMI 4
Warm Up DOC Intake Temperature Sensor Circuit: circuit voltage low / shorted low - 3152 SPN 4809 FMI 3
Warm Up DOC Intake Temperature Sensor Circuit: circuit voltage high / shorted high - 3166 SPN 4809 FMI 13
Warm Up DOC Intake Temperature Sensor Swapped: out of calibration - 3167 SPN 3556 FMI 18
Doser: reading below normal (moderately 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 3156 mean?
Cummins fault code 3156 is J1939 SPN 4810 FMI 4: Aftertreatment Warm Up Diesel Oxidation Catalyst Outlet Temperature Sensor Circuit - Voltage below normal. In plain terms: warm up doc outlet temperature sensor circuit: circuit voltage low / shorted low.
Can I keep driving with Cummins code 3156?
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 3156?
SPN 4810 identifies the part or system (Aftertreatment Warm Up Diesel Oxidation Catalyst Outlet Temperature). FMI 4 describes the type of failure: circuit voltage low / shorted low.
What usually causes Cummins code 3156?
The most common causes are: temperature sensor or sensor module failed; aftertreatment fuel doser, shutoff valve or pressure sensor wiring fault; connector heat damage.
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.