CAT Engine 76 Fault Code: Cylinder #7 Injector : Current Above Normal
Also called Cylinder #7 Current Above Normal, Cylinder #7 Injector : Current Below Normal, Cylinder #7 Injector Short, Cylinder #7 Injector current above normal, Cylinder #7 Injector short, Cylinder #7 Injector:Current Above Normal, Cylinder 7 Shorted, Injector Cylinder 7 Short, Injector Cylinder 7 short
Cylinder #7 Injector : Current Above Normal · ai-assisted, editor-reviewed · Last updated 2026-07-21
TL;DR
CAT code 76 (SPN 7 / FMI 6) means the ECM has detected a short to ground or a short across the electrical load on the Cylinder #7 injector solenoid circuit. High current flow triggers the code, and the ECM disables that solenoid circuit to prevent damage, then periodically retries firing it.
Medium severity. The engine will keep running because the ECM retries the disabled solenoid circuit periodically, but the affected cylinder will misfire or run rough until the short is fixed. Ongoing high current can damage the injector solenoid or engine harness if left unaddressed, so treat this as something to diagnose within the shift, not something to ignore long term.
What does CAT Engine error code 76 mean?
This code applies to CAT engines with Electronic Unit Injectors (EUI), including the C15, C175, C27, and C32. Each injector has two solenoids, and the ECM sends a 105 volt pulse to each solenoid at the correct time and duration for the current engine load and speed.
The ECM continuously monitors current flow through each solenoid circuit. Code 76 specifically means high current flow was detected, pointing to a short to ground or a short across the electrical load, often described as an internal solenoid short. This is different from code 75 (Current Below Normal), which points to low current flow, an open circuit, or a short to battery voltage instead.
When the ECM sees this condition, it disables the Cylinder #7 solenoid circuit to protect it from damage, then periodically retries firing the injector. If the short is still present, this disable-and-retry cycle repeats indefinitely until the problem is corrected, which is why the fault can come and go on a scan tool or diagnostic lamp.
What triggers a CAT Engine 76 code?
The code sets when the ECM detects high current flow through the Cylinder #7 injector solenoid circuit after unsuccessful attempts to fire that solenoid, consistent with FMI 06 (short to ground or short across the electrical load, i.e. an internal solenoid short).
Common causes of 76
- Short to ground or short across the electrical load inside the injector solenoid (internal solenoid short)
- Damaged or corroded injector connectors
- Damaged engine wiring harness, including the harness between the ECM and the valve cover base, or the harness under the valve cover
- Faulty or failed injector solenoid
- Problem elsewhere in the fuel system affecting cylinder #7
- A malfunctioning cylinder
- Improper injector adjustment and/or engine valve clearance
- Intermittent wiring or connector problems that only show up under vibration or heavy load
- Faulty ECM (less common, but listed as a possible cause if wiring and injector check out)
How to troubleshoot CAT Engine 76: first checks
- Let the engine reach normal operating temperature before testing, since injector solenoid problems typically show up once the engine is warmed up and under vibration or heavy load
- Inspect injector connectors at Cylinder #7 for corrosion, damage, or loose pins, since a short across the load often traces back to compromised connector insulation
- Trace and inspect the engine wiring harness and the harness between the ECM and valve cover base, and the harness under the valve cover, looking for chafed insulation that could short the signal wire to ground or to another powered wire
- Flex and wiggle the harness and connectors near Cylinder #7 while monitoring the circuit, since problems here are often intermittent and only appear under vibration
- Check injector adjustment and engine valve clearance for Cylinder #7, since improper adjustment is a listed cause
- Test the injector solenoid itself for an internal short if wiring and connectors check out clean
- Rule out fuel system problems specific to Cylinder #7 before condemning electrical components
How the code clears
No separate clearing step is listed for this code beyond correcting the underlying short. The ECM will automatically stop retrying and disabling the circuit once the short to ground or short across the load is repaired, since the disable-and-retry sequence only continues while the fault condition remains present.
Affected models and serial ranges
76 appears in our records across 4 CAT Engine models. Match your machine by model and serial number.
| Model | Serial ranges |
|---|---|
| C15 | Serial range not listed in source records |
| C175 | 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 76 mean?
It means the ECM detected high current flow in the Cylinder #7 injector solenoid circuit, consistent with a short to ground or a short across the electrical load, sometimes described as an internal solenoid short. The ECM disables that solenoid circuit and periodically retries firing it until the short is fixed.
Can I keep running the engine with code 76 active?
The engine will typically keep running since the ECM retries the disabled circuit periodically, but Cylinder #7 will likely misfire or contribute little power while the fault is active. Running for extended periods with an internal solenoid short risks further damage to the solenoid or harness, so it should be diagnosed promptly.
What is the difference between code 76 and code 75?
Code 75 (Cylinder #7 Injector Current Below Normal) points to low current flow, typically from an open circuit, a short to battery voltage, or a break in the wiring. Code 76 points to the opposite: high current flow from a short to ground or a short across the electrical load, often an internal solenoid short. If your symptom is low or no current, check the code 75 page instead.
What voltage does the injector solenoid normally see?
The ECM sends a 105 volt pulse to each injector solenoid, timed and sized for the current engine load and speed. Code 76 is triggered when the current draw during that pulse is abnormally high rather than a voltage-level issue on its own.
Why does this fault seem to come and go?
Injector solenoid problems commonly appear once the engine is warmed up and under vibration or heavy load, so a fault that's intermittent at idle or cold may become active during normal work. Wiring and connectors can also have damage that only shows up when flexed under vibration.
Could this be an ECM problem instead of wiring or the injector?
It's possible but less likely. Wiring, connectors, and the injector solenoid itself are the more common causes and should be ruled out first. A faulty ECM is listed as a possible cause only after the harness, connectors, and injector have been checked and cleared.
Will replacing the injector automatically fix code 76?
Not necessarily. The listed causes include damaged connectors, harness problems between the ECM and valve cover base, harness problems under the valve cover, and improper valve clearance or injector adjustment, in addition to a failed injector solenoid. Diagnose the wiring and adjustment before assuming the injector itself is bad.