CAT Engine 26065 Fault Code: Cylinder #3 Injector Actuator #2:Current Below Normal
Also called Cylinder #3 Injector Actuator #2 - Current Below Normal, Cylinder #3 Injector Actuator #2 : Current Below Normal
Cylinder #3 Injector Actuator #2:Current Below Normal · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
CAT code 26065 (SPN 3661 / FMI 5) means the ECM detected low current flow through the #2 solenoid circuit of the #3 cylinder's Electronic Unit Injector. It usually points to wiring, connector, or injector solenoid problems rather than a software fault, and it commonly shows up once the engine is at operating temperature or under load and vibration.
High severity. A single injector running with low or no current can cause misfire, rough running, power loss, and possible cylinder-to-cylinder imbalance. It will not usually shut the engine down immediately, but ignoring it risks further wiring or injector damage and uneven engine load.
What does CAT Engine error code 26065 mean?
This code applies to CAT C13, C15, C18, C27, and C32 engines equipped with Electronic Unit Injectors (EUI). Each injector has two solenoids, and the ECM sends 105 volt pulses to each solenoid at a precise time and duration based on engine load and speed.
The ECM continuously monitors current flow through each solenoid circuit. Code 26065 sets when the ECM detects low current flow on the #2 solenoid circuit for the #3 cylinder injector. When this happens, the ECM keeps trying to fire that injector rather than shutting the circuit down.
This is different from a high-current short circuit fault, where the ECM would disable the solenoid circuit to prevent damage. With low current (FMI 5), the concern is usually an open or high-resistance connection somewhere in the circuit rather than a dead short.
Common causes of 26065
- 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 or damaged harness section between the ECM and the valve cover base, or under the valve cover itself
- A faulty or failing injector solenoid inside the #3 cylinder injector
- An intermittent wiring or connector problem that only shows up under vibration or heavy load once the engine is warmed up
- A faulty ECM (listed as a possible cause if wiring and injector both check out good)
How to troubleshoot CAT Engine 26065: first checks
- Let the engine reach normal operating temperature before testing, since these faults often only appear when the engine is warmed up and under load or vibration
- Inspect all connectors and wiring for the #3 injector solenoid circuit for corrosion, looseness, chafing, or heat damage
- Wiggle-test the harness and connectors while watching for the code to reset, since intermittent opens often only show up under vibration
- Check the harness between the ECM and the injector connector for continuity and confirm there is no open circuit
- Check the harness between the ECM and the valve cover base, and the harness under the valve cover, for damage or an open circuit
- If wiring and connectors check out good, test the injector solenoid itself and be prepared to replace the injector
- If the injector and harness both test good, consider the ECM as a possible cause
How the code clears
No separate clearing procedure is listed for this code. Once the wiring, connector, harness, or injector problem is repaired, the ECM should stop logging new occurrences on its own during normal operation. Confirm the fix by running the engine at operating temperature and under load or vibration, since that is when this fault typically reappears if the repair did not resolve it.
Affected models and serial ranges
26065 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 fault code 26065 mean?
It means the ECM detected low current flow through the #2 solenoid circuit of the #3 cylinder's injector. It is logged as SPN 3661 with FMI 5, which specifically indicates a current-below-normal condition, usually caused by wiring, connector, or harness problems rather than the injector solenoid always being at fault.
Which CAT engines can throw code 26065?
This code applies to the C13, C15, C18, C27, and C32 engine models equipped with Electronic Unit Injectors.
Can I keep running the engine with this code active?
The ECM will keep trying to fire the affected injector, so the engine will likely keep running, but expect rough running, misfire, or power loss on that cylinder. It is best treated as a high-priority repair rather than something to ignore for an extended period.
Why does this code often only show up when the engine is warm?
Problems with injector solenoid wiring and connectors typically appear once the engine reaches normal operating temperature and is under load or vibration. Heat and vibration can cause marginal connections or chafed wiring to open intermittently, which is why testing should be done under those same conditions.
Is this a wiring problem or an injector problem?
answer
Do I need to replace the ECM for this code?
Not usually. A faulty ECM is listed as a possible cause, but it should only be considered after the wiring, connectors, harness, and injector solenoid have all been checked and ruled out.
Is there a reset procedure after repairing the wiring or injector?
No reset procedure is listed for this code. Once the underlying wiring, connector, harness, or injector fault is repaired, the ECM should stop generating new occurrences during normal operation.