What Does P1273 Mean?
The ECM has detected a high-to-low side short circuit in the cylinder #8 fuel injector driver circuit. This code is specific to V8 and larger engines. The short between the injector's high-side power and low-side control wires bypasses normal ECM control, causing cylinder #8 to misfire. The engine will run rough with reduced power, particularly from the affected bank.
Safety Warning
Persistent cylinder #8 misfire causes rough running, vibration, and reduced power. On V8 engines, this affects one entire bank's contribution. Unburned fuel can severely damage the catalytic converter. The shorted circuit risks further ECM driver damage.
Common Causes
35%
Damaged injector wiring harness with high and low side conductors making unintended contact near cylinder #8
30%
Failed cylinder #8 fuel injector with internally shorted coil windings
20%
Corroded or moisture-damaged connector at the cylinder #8 injector
15%
ECM internal driver failure on the cylinder #8 injector output
Diagnostic Steps
1
Check for P0308 (cylinder #8 misfire) and other injector circuit codes across all cylinders to assess the scope of the problem.
2
Locate cylinder #8 and disconnect its fuel injector connector. Inspect for heat damage, corrosion, or contamination between the connector pins.
3
Measure the injector coil resistance and verify it is within the manufacturer's specified range. Test for shorts between the terminals and the injector body.
4
With the injector disconnected, verify no continuity between the two harness-side wires at the connector — continuity indicates a wiring short.
5
Swap the cylinder #8 injector with a known-good injector from another cylinder, clear codes, and run the engine to isolate the fault to the injector, wiring, or ECM.
Estimated Repair Cost
$100 - $550
Parts + labor, varies by vehicle and location
The ECM has detected a high-to-low side short circuit in the cylinder #8 fuel injector driver circuit. This code is specific to V8 and larger engines. The short between the injector's high-side power and low-side control wires bypasses normal ECM control, causing cylinder #8 to misfire. The engine w...
The most common cause of P1273 (Cylinder #8 High To Low Side Short) is: Damaged injector wiring harness with high and low side conductors making unintended contact near cylinder #8
Typical repair costs for P1273 range from $100 to $550, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Persistent cylinder #8 misfire causes rough running, vibration, and reduced power. On V8 engines, this affects one entire bank's contribution. Unburned fuel can severely damage the catalytic converter. The shorted circuit risks further ECM driver damage.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1273 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel Injection System
Difficulty
Type
Manufacturer
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