Komatsu Track Dozer CA272 Fault Code: IMV/PCV1 Open Error
Also called Disconnection is Detected at Drive Circuit of Supply Pump Actuator, IMV/PCV1 Disconnection: Disconnection, IMV/PCV1 Open Error (Engine Controller System), IMV/PCV1 Open: Open, IMV/PCV1 disconnection: Disconnection, IMV/PCV1 disconnection: Disconnection (Engine controller system), PCV1 Disconnection (Left Bank): Disconnection, PCV1 Disconnection: Disconnection, PCV1 Open Error, PVC1 Open Error
IMV/PCV1 Open Error · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
CA272 sets when the engine controller detects an open circuit in the supply pump actuator drive circuit, also called SCV or PCV1/IMV. It means engine output is reduced and engine speed may become unstable, with common rail fuel pressure rising above the command value. Action Level is listed as L03.
Medium severity. Komatsu lists this as Action Level L03 with no automatic derate or shutdown noted. Engine output is reduced and speed can become unstable, so it should be diagnosed promptly, but the machine is generally still operable in the short term.
What does Komatsu Track Dozer error code CA272 mean?
CA272 points to an open circuit in the drive circuit of the supply pump actuator, referred to across Komatsu documentation as the SCV (supply pump control valve), PCV1, or IMV depending on the model and manual revision. This valve controls how much fuel the supply pump sends to the common rail, so the engine controller relies on a working drive circuit to manage rail pressure and fueling.
When the controller detects the circuit is open rather than completing a normal pulsed signal path, it logs CA272. Komatsu notes that under normal running conditions, a pulse voltage of approximately 24V is applied to the SCV/PCV1, but this pulse cannot be read with a standard multimeter because it is a switched pulse signal rather than steady DC.
The practical effects reported on the machine are reduced engine output, engine speed that does not stabilize, and common rail fuel pressure rising above the commanded value. Komatsu's own 'Action of Controller' field is listed as N/A or 'none in particular' across all variants, meaning there is no separate automatic protective action described beyond the output reduction itself.
Common causes of CA272
- Defective wiring harness connector at the supply pump actuator (SCV/PCV1/IMV)
- Defective supply pump actuator or SCV/PCV1 valve itself (internal open circuit)
- Open circuit or short circuit in the wiring harness between the controller and the actuator
- Ground fault in the wiring harness, meaning unintended contact with the ground circuit
- Hot short circuit in the wiring harness, meaning unintended contact with the 24V circuit
- Defective engine controller
How to troubleshoot Komatsu Track Dozer CA272: first checks
- Turn the starting switch to the ON position, since this is the method Komatsu lists for reproducing the failure code, and confirm the code is active before starting teardown
- Visually inspect the harness connector at the supply pump actuator for corrosion, bent pins, or a connector that is not fully seated
- Trace the wiring harness between the engine controller and the supply pump actuator looking for chafing, pinched sections, or exposed conductors that could cause an open, short, or ground fault
- Check for a possible hot short by looking for harness contact against a 24V circuit, which can mimic or accompany this open-circuit fault
- Be aware that Komatsu specifically notes the troubleshooting socket for this circuit is a female-only connector that will not mate with the sensor harness side, so it cannot be used as a simple T-adapter for an open-circuit check; plan on backprobing or using proper breakout tooling instead
- If wiring and connectors check out, suspect the supply pump actuator (SCV/PCV1) internally, or as a last step, the engine controller itself
How the code clears
No separate reset or clearing procedure is listed for this code. Since the 'Action of Controller' field is documented as N/A or 'none in particular' across all variants, repair centers on correcting the open circuit condition, whether that is a connector, harness, actuator, or controller issue, and then verifying the code does not reset after the starting switch is cycled to ON.
Affected models and serial ranges
CA272 appears in our records across 3 Komatsu Track Dozer models. Match your machine by model and serial number.
| Model | Serial ranges |
|---|---|
| D22 | Serial range not listed in source records |
| D61 | Serial range not listed in source records |
| D65 | Serial range not listed in source records |
Frequently asked questions
What does CA272 mean on a Komatsu dozer?
It means the engine controller detected an open circuit in the drive circuit of the supply pump actuator, known as the SCV, PCV1, or IMV depending on the manual. This reduces engine output and can cause unstable engine speed.
Can I still operate the dozer with a CA272 code active?
Komatsu lists this as Action Level L03 with no forced shutdown described, but engine output is reduced and speed may not stabilize, and common rail fuel pressure can rise above the commanded value. It should be diagnosed and repaired promptly rather than run indefinitely.
Why can't I just check the SCV/PCV1 circuit with a multimeter?
Under normal running conditions the valve sees a pulse voltage of approximately 24V, and a standard multimeter cannot accurately read this pulsed signal. Komatsu also notes the troubleshooting socket for this circuit is female-only and will not connect to the sensor harness side as a T-adapter, so a different testing approach is needed.
What parts commonly cause a CA272 fault?
Komatsu lists a defective harness connector, a defective supply pump actuator (SCV/PCV1) with an internal open circuit, an open or short circuit in the wiring harness, a ground fault in the harness, a hot short against the 24V circuit, or a defective engine controller.
Is CA272 the same as SCV, PCV1, or IMV disconnection codes?
Yes. Komatsu uses several overlapping descriptions for this code across model documentation, including 'Supply Pump Actuator Disconnection,' 'IMV/PCV1 Open Error,' and 'PCV1 Disconnection,' all referring to the same open circuit condition in the supply pump control valve drive circuit.
Does CA272 affect fuel pressure?
Yes, several Komatsu variants of this code note that common rail fuel pressure can rise above the command value when this open circuit is present, in addition to engine speed instability.