Cummins fault code 6555
EGR Valve Control Circuit: not responding / out of adjustment
What it means
Cummins' description: EGR Valve Control Circuit - Mechanical system not responding or out of adjustment.
SPN 2791 is Engine Exhaust Gas Recirculation 1 (EGR1) Valve Control. FMI 7 means the ECM commanded something to move or change and it didn't respond the way it should: sticking, binding, worn, or out of adjustment.
The EGR system routes a measured amount of cooled exhaust back into the intake to lower combustion temperature and NOx. It uses a valve, a cooler, temperature sensors and a differential pressure sensor to measure flow.
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
One EGR code that clears, with no power loss, smoke or coolant loss.
Schedule a repair
Amber lamp, rough running, more soot, or slow regens. EGR problems load the DPF and get worse with time, so schedule it.
Stop and get help
Coolant disappearing with white smoke, or a stop lamp. Shut it down. A leaking EGR cooler can push coolant into the engine and cause hydrolock or head gasket damage.
Common causes
The sensor reading itself is out of range or the condition is real, so look at the system:
- EGR valve sticking from soot buildup
- Clogged EGR cooler restricting flow
- Leaking EGR cooler (watch for coolant loss or white smoke)
- Boost or exhaust pressure problem affecting flow
- Real high EGR temperature from a failing cooler
What you can check before calling
- Check coolant level. Unexplained loss can point to an EGR cooler leak
- Look for white smoke or a sweet coolant smell from the exhaust
- Look for soot tracks or loose hoses around the EGR valve and pressure sensor
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. 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
- 1893 SPN 2791 FMI 9
EGR Valve Control Circuit: abnormal update rate - 1896 SPN 2791 FMI 13
EGR Valve Controller: out of calibration - 1961 SPN 2791 FMI 15
EGR Valve Control Circuit Over Temperature: reading above normal (least severe) - 2349 SPN 2791 FMI 5
EGR Valve Control Circuit: circuit open / current low - 2353 SPN 2791 FMI 6
EGR Valve Control Circuit: circuit grounded / current high - 2357 SPN 2791 FMI 7
EGR Valve Control Circuit: not responding / out of adjustment
Related EGR codes
- 4485 SPN 5838 FMI 31
EGR Valve Malfunction: condition exists - 3138 SPN 5019 FMI 2
Engine EGR Outlet Pressure: erratic or intermittent signal - 3137 SPN 5019 FMI 4
Engine EGR Outlet Pressure Sensor Circuit: circuit voltage low / shorted low - 3136 SPN 5019 FMI 3
Engine EGR Outlet Pressure Sensor Circuit: circuit voltage high / shorted high - 2962 SPN 412 FMI 16
EGR Temperature: reading above normal (moderately severe) - 2961 SPN 412 FMI 15
EGR Temperature: reading above normal (least 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 6555 mean?
Cummins fault code 6555 is J1939 SPN 2791 FMI 7: EGR Valve Control Circuit - Mechanical system not responding or out of adjustment. In plain terms: egr valve control circuit: not responding / out of adjustment.
Can I keep driving with Cummins code 6555?
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 6555?
SPN 2791 identifies the part or system (Engine Exhaust Gas Recirculation 1 (EGR1) Valve Control). FMI 7 describes the type of failure: not responding / out of adjustment.
What usually causes Cummins code 6555?
The most common causes are: eGR valve sticking from soot buildup; clogged EGR cooler restricting flow; leaking EGR cooler (watch for coolant loss or white smoke).
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