CAT 46 Fault Code: Engine Injector Cylinder #04 : Current Above Normal
Engine Injector Cylinder #04 : Current Above Normal · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
CAT code 46, SPN 654 FMI 6, means the ECM detected high current flow (short circuit) on the injector solenoid circuit for cylinder #4 on C13 or C15 engines. The ECM disables that solenoid circuit to prevent damage, then periodically retries firing the injector. If the short remains, this cycle repeats until the problem is fixed.
High severity. The ECM protects itself by disabling the injector solenoid circuit, so the engine may run rough or lose power on that cylinder, and the fault will keep recurring until repaired. It is not an immediate shutdown risk, but ignoring it risks continued misfire, harness damage, or injector failure.
What does CAT error code 46 mean?
This code applies to CAT C13 and C15 engines equipped with Electronic Unit Injectors (EUI). Each injector has a solenoid that the ECM fires with 105 V pulses timed for engine load and speed. The ECM constantly monitors current flow through each injector solenoid circuit.
Code 46 specifically means the ECM saw high current flow, a short circuit, on the cylinder #4 injector solenoid circuit. When this happens, the ECM disables that solenoid circuit to prevent further damage from the excess current, but it will periodically attempt to fire the injector again. If the short circuit is still present, this disable-and-retry sequence repeats continuously until the underlying problem is corrected.
Note that FMI 6 (high current/short) is distinct from the low current/open circuit condition, which the ECM also monitors but which sets a different diagnostic condition on the same circuit.
Common causes of 46
- Failed injector (internal solenoid short)
- Wiring between the ECM and the valve cover damaged, chafed, or shorted
- Wiring under the valve cover for the injector harness damaged or shorted
- Plugged oil outlet port on the exhaust valve rocker arm, which can affect injector operation
How to troubleshoot CAT 46: first checks
- Run the engine to normal operating temperature before testing, since injector solenoid problems typically show up once the engine is warmed up and under load or vibration
- Inspect wiring and connectors between the ECM and the valve cover carefully for chafing, corrosion, or damage, paying close attention since problems may only appear under vibration
- Inspect the injector harness wiring under the valve cover for the same kind of damage
- Check the oil outlet port on the exhaust valve rocker arm for cylinder #4 for blockage
- Test the injector solenoid circuit for cylinder #4 for a short circuit condition using appropriate electrical test procedures
- With the engine under load or heavy vibration, watch for intermittent current spikes that might not show up at idle
How the code clears
No separate clearing step is listed. The code should clear once the short circuit in the injector, ECM-to-valve-cover wiring, or under-valve-cover harness is repaired and the ECM verifies normal current flow through the cylinder #4 injector solenoid circuit again.
Affected models and serial ranges
46 appears in our records across 2 CAT 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 |
Frequently asked questions
What does CAT fault code 46 mean?
It means the ECM detected high current flow, a short circuit, on the injector solenoid circuit for cylinder #4 on a C13 or C15 engine. The ECM disables that circuit to protect it and periodically retries firing the injector.
Can I keep driving or working with code 46 active?
The engine will likely run, but with reduced performance or rough running since the ECM disables the affected injector solenoid circuit when it detects the short. It's best to diagnose and repair as soon as practical rather than run indefinitely on a disabled cylinder.
Why does this fault often show up only when the engine is warm or under load?
Problems with injector solenoids and their wiring commonly appear once the engine reaches normal operating temperature and experiences vibration from heavy loads. Wiring or connector issues especially may only fault out under those vibration conditions.
What parts should I inspect first for code 46?
Check the cylinder #4 injector itself, the wiring between the ECM and the valve cover, the injector harness wiring under the valve cover, and the oil outlet port on the exhaust valve rocker arm for blockage.
Is code 46 the same as an open circuit injector fault?
No. Code 46 (FMI 6) is specifically a high current or short circuit condition. A low current or open circuit condition on the same injector solenoid is a separate diagnostic condition.
Will the code clear itself after repair?
No separate clearing procedure is listed. Once the short is repaired and the ECM sees normal current flow through the injector solenoid circuit, the fault should stop being active.