CAT Engine 2672 Fault Code: Incorrect Engine Shutdown Switch inputs
Also called Incorrect Engine Shutdown Switch Inputs, Remote Shutdown Input : Erratic, Intermittent, or Incorrect, Remote Shutdown Input Erratic, Intermittent, or Incorrect, Remote Shutdown Input erratic, intermittent, or incorrect, Shutdown Inputs Are Incorrect
Incorrect Engine Shutdown Switch inputs · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
CAT code 2672 (SPN 267, FMI 2) means the ECM sees both engine shutdown switch inputs reading the same state, either both open or both closed, instead of one open and one closed as expected. The ground level or remote shutdown feature is disabled when this is active, and depending on engine state, the engine may not be allowed to start.
High severity. The engine may run fine while this code is active, but on many of these ECM strategies the control will refuse to start the engine once it is shut off until the fault is cleared. Treat it as a stop-soon issue rather than an emergency while running, but a must-fix before the next shutdown.
What does CAT Engine error code 2672 mean?
This code covers the ground level or remote engine shutdown switch circuit on CAT C11, C13, C15, C175, C27, and C32 engines. That switch is normally mounted outside the cab, often near the radiator cowling or under a red cover guard, so someone on the ground can shut the engine down for maintenance without climbing into the cab.
The switch sends two signals to the ECM, one from a normally open contact and one from a normally closed contact. In normal operation, one of these reads roughly 11.5 volts DC (within 0.5 volts) while the other reads below 0.5 volts DC. The ECM expects these two signals to always disagree with each other. Code 2672 sets when both inputs agree, either both showing near 11.5 volts or both showing below 0.5 volts.
When this happens, the ECM disables the ground level shutdown feature so the switch can no longer be trusted to shut the engine down. If the engine is already running, most versions let it keep running. If the engine is stopped, the ECM will not allow it to start again until the switch is returned to the RUN position and the keyswitch is cycled OFF and back ON, and on some versions the fault needs to be corrected first.
What triggers a CAT Engine 2672 code?
The ECM logs this code when both shutdown switch inputs are in the same electrical state at the same time: both open (reading about 11.5 volts DC ± 0.5 volts) or both closed (reading less than 0.5 volts DC). On one ECM variant, the code also requires that the ECM has been powered for 3 seconds and that no CID-FMI is already logged for it before it will set.
Common causes of 2672
- Damaged, corroded, or loose connectors and wiring at the shutdown switch or along the harness
- A general problem within the wiring harness itself, including chafed or pinched wiring
- An intermittent connection issue that only shows up under vibration or temperature changes
- A faulty or worn ground level/remote shutdown switch that fails to open or close one of its contacts properly
- A faulty relay in circuits that use one for the shutdown signal
- A failed or failing Electronic Control Module (ECM) that misreads the switch inputs
How to troubleshoot CAT Engine 2672: first checks
- Inspect the ground level shutdown switch and its red cover guard for physical damage, and confirm the switch itself moves freely between RUN and SHUTDOWN positions
- Check all connectors in the shutdown switch circuit for corrosion, moisture, loose pins, or backed-out terminals, both at the switch and along the harness back to the ECM
- With a meter, check voltage at the ECM shutdown signal inputs: one line should read about 11.5 volts DC (± 0.5 volts) and the other less than 0.5 volts DC with the switch in RUN. If both read the same, that confirms the fault condition
- Trace the harness between the switch and the ECM for chafe points, pinches, or exposed wire, especially near the radiator cowling or front bumper area where the switch is often mounted on truck applications
- If wiring and connectors check out, test the switch itself for proper open/closed operation on both contacts before condemning the ECM
How the code clears
No separate clearing step is listed beyond fixing the underlying wiring, connector, switch, or ECM issue. On several versions, once both switch inputs show correctly opposite states again, return the switch to the RUN position and cycle the keyswitch OFF and then back ON before the ECM will allow the engine to start. No numeric reset delay is given.
Affected models and serial ranges
2672 appears in our records across 6 CAT Engine models. Match your machine by model and serial number.
| Model | Serial ranges |
|---|---|
| C11 | Serial range not listed in source records |
| C13 | Serial range not listed in source records |
| C15 | Serial range not listed in source records |
| C175 | Serial range not listed in source records |
| C27 | Serial range not listed in source records |
| C32 | Serial range not listed in source records |
Frequently asked questions
Will code 2672 stop my CAT engine from starting?
It depends on the engine state when the fault is detected. If the engine is already running when both switch inputs read the same, several versions let it continue running. If the engine is not running, the ECM will not allow it to start until the switch inputs are correct again and the keyswitch is cycled OFF and back ON.
What does SPN 267 FMI 2 mean on a CAT engine?
SPN 267 identifies the engine shutdown switch circuit and FMI 2 indicates an erratic, intermittent, or incorrect signal. Together they correspond to CAT code 2672, meaning the ECM sees both shutdown switch inputs in the same state instead of opposite states.
Where is the ground level shutdown switch located?
It is mounted outside the operator's cab, typically under a red cover guard, so maintenance staff can shut the engine down without entering the cab. On some truck applications it sits on the front radiator cowling near the front bumper on the driver's side.
Can I still use a diagnostic scan tool if this code is active?
Yes. The ECM stays active and communicates with a diagnostic scan tool even while the ground level shutdown feature is disabled by this fault.
What voltage should I see at the shutdown switch inputs if everything is working?
With the switch in the RUN position, one input should read about 11.5 volts DC (± 0.5 volts) and the other should read less than 0.5 volts DC. If both inputs match each other, that is the fault condition behind code 2672.
Is code 2672 likely a switch problem or a wiring problem?
Both are common causes, along with harness damage, corrosion at connectors, and occasionally a bad relay or a failed ECM. Checking connectors and wiring first is the quickest way to rule out the cheaper fixes before replacing the switch or ECM.
Does this code mean the engine shutdown feature is broken permanently?
Not necessarily. The ECM disables the ground level shutdown feature only while the fault condition is present. Once the wiring, connector, switch, or ECM issue is repaired and the switch inputs read correctly again, normal shutdown function should return.