CAT 93 Fault Code: Intake Valve Actuator #3 not responding

What does CAT error code 93 mean?

The Intake Valve Actuation (IVA) system uses pressurized engine oil, controlled by the ECM, to delay the closing of the intake valves on cylinders 3 and 4. The system relies on a check valve, a pressure sensor, a control valve with a coil and spool, and an actuator located under the valve cover that uses both oil pressure and electrical commands from the ECM to hold the rocker arm down.

Code 93 fires in several forms: a current high or current low (open circuit) condition on the actuator solenoid, or the actuator simply not responding to ECM commands. The current low/open circuit versions are detected specifically when the ECM tries and fails to energize the actuator across five consecutive attempts while battery voltage stays above 9 VDC for the last two seconds.

The not-responding version means the actuator is active but not behaving as commanded. This version forces an engine derate for as long as the code is active, and if the code logs repeatedly, the derate will persist until the code is cleared, only to return if the root cause isn't fixed.

What triggers a CAT 93 code?

For the current high/low (open circuit) forms: the ECM detects a low current condition during five consecutive attempts to energize the intake valve actuator for the affected cylinder (3 or 4), while battery voltage is above 9 VDC for the previous two seconds. For the not-responding form: the intake valve actuator is active but is not working properly in response to ECM commands.

Common causes of 93

• Failed or contaminated intake valve actuation oil pressure sensor
• Oil leak near the solenoids or under the valve cover
• Loose purge orifice
• Failed solenoid inside the control valve or actuator
• Debris in the intake valve actuator system
• Failed or damaged check valve
• Failed cylinder (confirm with cylinder cut out tests)
• Improper lash settings on the intake valve actuator, or incorrect actuator adjustment
• Failed intake valve actuator itself
• ECM connection or harness fault, including wiring between the valve cover connector and the ECM connector
• Wiring fault at the valve cover connector for the affected solenoid
• ECM failure

How to troubleshoot CAT 93: first checks

1. 1Retrieve and confirm which specific form of code 93 is active (current high, current low, or not responding) and which cylinder, 3 or 4, is affected, since the repair path differs.
2. 2Inspect the valve cover connector and harness wiring between the ECM and the affected solenoid for corrosion, loose pins, chafing, or open circuits.
3. 3Check for oil leaks near the solenoids, around the control valve, or under the valve cover base that could starve the actuator rail of pressure.
4. 4Verify valve lash settings and actuator adjustment on the affected cylinder are within spec per the engine's service adjustment procedure.
5. 5Inspect the check valve and purge orifice for looseness, debris, or damage that could let rail pressure bleed off.
6. 6If a specific cylinder is suspected of a mechanical problem, perform a cylinder cut out test to confirm.

How the code clears

No separate clearing step is listed beyond fixing the root cause. For the not-responding version, note that if the code has logged multiple times, the engine derate will stay in effect until the code is actively cleared, and it will return under derate again if the underlying problem is not resolved.

Affected models and serial ranges

93 appears in our records across 3 CAT models. Match your machine by model and serial number.