What Does P0295 Mean?
The ECM has detected an excessively high voltage or current level on the cylinder 12 fuel injector circuit. This indicates an electrical fault in the injector wiring or the injector itself, such as a short to power, shorted coil windings, or a faulty ECM driver. On engines with 12 cylinders (V12 or large diesel configurations), this can cause over-fueling, rough running, or black smoke from the affected cylinder.
Common Causes
35%
Wiring harness short to battery voltage in the cylinder 12 injector circuit from chafing or heat damage
30%
Internally shorted cylinder 12 fuel injector coil causing excessive current flow
15%
Corroded or water-damaged injector connector at cylinder 12
12%
ECM injector driver failure producing incorrect voltage output for cylinder 12
8%
Incorrect injector installed (wrong impedance rating) on cylinder 12
Diagnostic Steps
1
Disconnect the cylinder 12 injector and measure coil resistance; compare to specification (solenoid type typically 12-16 ohms, piezo type 0.5-1.2 ohms). A significantly low reading indicates a shorted coil.
2
With the injector disconnected, use a DVOM to check both harness wires for short to battery voltage and short to ground; neither should be present with key on engine off.
3
Visually inspect the cylinder 12 injector harness from the ECM to the injector for chafing against the engine block, exhaust, or other components.
4
Test by swapping cylinder 12 injector with one from an adjacent known-good cylinder; clear codes and operate the engine to determine if the code follows the injector or stays at the position.
5
If wiring and injector are good, use an oscilloscope to capture the cylinder 12 injector driver waveform from the ECM; compare peak voltage and current profile to a known-good cylinder.
Estimated Repair Cost
$150 - $1,200
Parts + labor, varies by vehicle and location
The ECM has detected an excessively high voltage or current level on the cylinder 12 fuel injector circuit. This indicates an electrical fault in the injector wiring or the injector itself, such as a short to power, shorted coil windings, or a faulty ECM driver. On engines with 12 cylinders (V12 or ...
The most common cause of P0295 (Cylinder 12 Injector Circuit High) is: Wiring harness short to battery voltage in the cylinder 12 injector circuit from chafing or heat damage
Typical repair costs for P0295 range from $150 to $1,200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
An injector circuit high condition can cause continuous fuel injection, leading to cylinder wash-down, oil dilution, and potential hydro-lock risk. Do not drive the vehicle extended distances. Repair promptly to prevent engine damage.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0295 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel Injection System
Difficulty
Type
Generic (SAE)
Recommended Tools
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