Cummins fault code · Engine brake and exhaust back pressure

Cummins fault code 2363

Engine Brake Actuator Driver Output 2 Circuit: circuit voltage low / shorted low

J1939 SPN1073
FMI4
LampAmber warning lamp
SystemEngine brake and exhaust back pressure

What it means

Cummins' description: Engine Brake Actuator Driver Output 2 Circuit - Voltage below normal, or shorted to low source.

SPN 1073 is Engine (Compression) Brake Output #2. 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 engine (compression) brake and exhaust back pressure valve help slow the truck and warm up the engine and aftertreatment. The ECM controls them with solenoids and monitors their position.

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.

How serious is it?

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.

Green

Keep an eye on it

A brake code that set once and the engine brake still works on all settings.

Yellow

Schedule a repair

The engine brake doesn't work on one or more settings, or slow warm-up. Get it fixed. You're relying more on the service brakes.

Red

Stop and get help

Back pressure valve stuck closed (big power loss, overheating exhaust), or no engine brake on steep grades with a heavy load. Don't haul heavy until it's repaired.

Common causes

FMI 4 is an electrical or signal fault, so start with the circuit:

  • Engine brake solenoid circuit open or shorted
  • Exhaust back pressure valve or position sensor fault
  • Connector under the valve cover or at the exhaust damaged

If the circuit checks out, the reading may be real. Other possibilities: exhaust back pressure valve stuck from soot; engine brake out of adjustment.

What you can check before calling

  • Test whether the engine brake works on each setting
  • Listen for the back pressure valve moving at startup
  • Look for damaged wiring near the exhaust

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, 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.

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 2363 mean?

Cummins fault code 2363 is J1939 SPN 1073 FMI 4: Engine Brake Actuator Driver Output 2 Circuit - Voltage below normal, or shorted to low source. In plain terms: engine brake actuator driver output 2 circuit: circuit voltage low / shorted low.

Can I keep driving with Cummins code 2363?

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 2363?

SPN 1073 identifies the part or system (Engine (Compression) Brake Output #2). FMI 4 describes the type of failure: circuit voltage low / shorted low.

What usually causes Cummins code 2363?

The most common causes are: engine brake solenoid circuit open or shorted; exhaust back pressure valve or position sensor fault; connector under the valve cover or at the exhaust damaged.

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