CAT Engine 26045 Fault Code: Cylinder #2 Injector Actuator #2:Current Below Normal
Also called Cylinder #2 Injector Actuator #2 - Current Below Normal, Cylinder #2 Injector Actuator #2 : Current Below Normal
Cylinder #2 Injector Actuator #2:Current Below Normal · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
CAT code 26045 (SPN 3660, FMI 5) means the ECM detected low current flow in the Cylinder #2 Injector Actuator #2 solenoid circuit. This affects C13, C15, C18, C27, and C32 engines with Electronic Unit Injectors. The ECM keeps trying to fire the injector, but low current usually points to a wiring, connector, or injector solenoid problem rather than a total failure.
Medium severity. The engine can typically keep running because the ECM continues attempting to fire the injector, but a persistent low-current fault on one cylinder means uneven combustion, possible misfire, rough running, and long-term wear. It should be diagnosed promptly rather than ignored, especially if it appears repeatedly under load.
What does CAT Engine error code 26045 mean?
CAT engines with Electronic Unit Injectors (EUI) use two solenoids per injector. The ECM sends 105 volt pulses to each solenoid at precise timing and duration based on engine load and speed. This lets the ECM control fuel delivery electronically instead of relying purely on mechanical injection timing.
The ECM constantly monitors current flow through each injector solenoid circuit. Code 26045 triggers when the ECM detects current flow through the Cylinder #2 Actuator #2 circuit that is below normal. Unlike a high-current short, which causes the ECM to disable the circuit to prevent damage, a low-current fault does not shut the circuit down. The ECM keeps trying to fire that injector every cycle.
This behavior means the engine may continue running with the fault present, but that cylinder's injector is not firing correctly and consistently. Left unaddressed, this can cause rough idle, power loss, poor fuel economy, or increased wear on the injector and related components.
Common causes of 26045
- Damaged, corroded, or loose connectors or wiring in the injector solenoid circuit
- An open circuit in the wiring harness between the ECM and the injector connector
- An open circuit in the harness between the ECM and the valve cover base, or under the valve cover itself
- Electronic problem with the injector itself, including a faulty injector solenoid
- Faulty or intermittent wiring connections that only show a problem under vibration or once the engine is warmed up
- A failed ECM (less common, but listed as a possible cause if wiring and injector both check out)
How to troubleshoot CAT Engine 26045: first checks
- Run the engine to normal operating temperature before testing. Many of these faults only appear once the engine is warmed up and under load, so testing cold can mask the problem.
- Inspect all connectors and wiring in the Cylinder #2 Injector Actuator #2 circuit for corrosion, looseness, or damage. Pay close attention to connector pins and harness routing near the valve cover base and under the valve cover.
- Check for vibration-related intermittent faults. Since problems often show up under heavy load or engine vibration, gently flex and move harness sections while monitoring for the code re-triggering, if your diagnostic tool allows real-time monitoring.
- Verify the harness between the ECM and the injector connector has no open circuit. Test continuity through the full length of the harness, not just at the ends.
- Inspect the injector solenoid itself once wiring and connectors are confirmed good. A bad injector solenoid is a listed cause and may require injector replacement.
- If wiring, connectors, and injector all test good, consider ECM failure as a possible cause, but treat this as a last resort after ruling out the more common wiring and injector issues.
How the code clears
No separate clearing step is listed. Once the underlying wiring, connector, injector, or ECM issue is repaired, the code should stop being generated as normal current flow is restored to the circuit. Confirm the repair by running the engine under conditions similar to when the fault originally occurred, including at normal operating temperature and under load, since intermittent faults may not show up during a quick idle check.
Affected models and serial ranges
26045 appears in our records across 5 CAT Engine models. Match your machine by model and serial number.
| Model | Serial ranges |
|---|---|
| C13 | Serial range not listed in source records |
| C15 | Serial range not listed in source records |
| C18 | 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
What does CAT code 26045 mean?
It means the ECM detected current flow below normal in the Cylinder #2 Injector Actuator #2 solenoid circuit. This is SPN 3660 with FMI 5, indicating a low-current electrical condition rather than a mechanical fault directly.
Can I keep operating the machine with code 26045 active?
The ECM will keep trying to fire the injector, so the engine may keep running, but that cylinder is not firing correctly. It is best to diagnose and repair the fault as soon as practical rather than run for extended periods, since it can cause rough running and added wear.
Which engines can show fault code 26045?
This code applies to CAT C13, C15, C18, C27, and C32 engines equipped with Electronic Unit Injectors.
Why does this fault only show up sometimes?
Injector solenoid wiring and connector problems often only appear once the engine is warmed up or under heavy load and vibration. A connector that looks fine at idle can fail intermittently once the engine heats up and starts vibrating under load, so testing should be done under those same conditions.
What usually causes low current on an injector actuator circuit?
The most common causes are damaged or corroded wiring and connectors, an open circuit somewhere in the harness between the ECM and the injector, or a faulty injector solenoid. A failed ECM is possible but far less common.
Do I need to replace the injector to fix code 26045?
Not necessarily. Wiring and connector problems are more commonly listed as causes than a bad injector. Injector replacement should only be done after wiring, connectors, and the harness have been thoroughly checked and ruled out.
Is there a specific reset procedure after repairing the fault?
No reset procedure is listed for this code. The fault should clear on its own once normal current flow is restored, but repairs should be verified by running the engine under load at normal operating temperature to confirm the problem does not return.