What Does P1274 Mean?
The ECM has detected a high-to-low side open circuit condition in the cylinder #4 fuel injector driver circuit. Unlike a short circuit, an open circuit means there is a break in the electrical path — either the high-side power feed or the low-side control wire is disconnected. The ECM cannot energize the cylinder #4 injector at all, resulting in a complete dead misfire on that cylinder.
Safety Warning
A completely dead cylinder #4 causes a constant misfire with rough running, vibration, and significant power loss. Unburned fuel will damage the catalytic converter rapidly. The engine may be difficult to drive safely in traffic with the reduced power.
Common Causes
30%
Broken wire in the cylinder #4 injector harness creating an open circuit
25%
Disconnected or backed-out pin in the cylinder #4 injector connector
25%
Failed fuel injector with open (burned out) internal coil winding
15%
Corroded connector terminal creating high resistance approaching an open condition
5%
ECM injector driver open-circuit failure
Diagnostic Steps
1
Check for cylinder #4 misfire code (P0304) and related injector codes (P1264, P1269) to map the full fault picture.
2
Disconnect the cylinder #4 injector connector and inspect both sides for backed-out pins, broken terminal locks, corrosion, or visible wire damage.
3
Measure the fuel injector coil resistance — an open reading (OL/infinity) confirms a burned-out injector coil. Normal is typically 11-18 ohms.
4
If the injector resistance is normal, use a multimeter to check continuity of each wire from the injector connector back to the ECM connector to find the open circuit location.
5
Repair any broken wires or damaged connectors, or replace the injector if its coil is open. Clear codes and verify the repair.
Estimated Repair Cost
$100 - $500
Parts + labor, varies by vehicle and location
The ECM has detected a high-to-low side open circuit condition in the cylinder #4 fuel injector driver circuit. Unlike a short circuit, an open circuit means there is a break in the electrical path — either the high-side power feed or the low-side control wire is disconnected. The ECM cannot energiz...
The most common cause of P1274 (Cylinder #4 High To Low Side Open) is: Broken wire in the cylinder #4 injector harness creating an open circuit
Typical repair costs for P1274 range from $100 to $500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
A completely dead cylinder #4 causes a constant misfire with rough running, vibration, and significant power loss. Unburned fuel will damage the catalytic converter rapidly. The engine may be difficult to drive safely in traffic with the reduced power.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1274 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel Injection System
Difficulty
Type
Manufacturer
Recommended Tools
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