What Does P0273 Mean?
This code indicates a cylinder 4 contribution or balance fault, with the ECM detecting that cylinder 4 is producing less power than the other cylinders. In some ECM implementations, P0273 specifically denotes the low-contribution side of the balance test for cylinder 4. The driver will experience rough running, misfires, and reduced engine output.
Common Causes
35%
Cylinder 4 fuel injector with degraded performance — restricted or worn
25%
Mechanical wear on cylinder 4 — piston rings or valve seat erosion
20%
Wiring or electrical issue reducing injector pulse delivery to cylinder 4
12%
Intake manifold gasket leak or port restriction at cylinder 4
8%
Exhaust system restriction affecting cylinder 4 breathing
Diagnostic Steps
1
Compare cylinder-by-cylinder contribution data in live PID data to confirm cylinder 4 is the weak performer and determine the magnitude of the imbalance.
2
Perform a relative compression test during cranking using the crankshaft sensor signal pattern — this quick, non-invasive test identifies compression-related issues without removing components.
3
Swap the cylinder 4 injector with a known-good cylinder, clear codes, and drive — track whether the contribution fault follows the injector or stays at position 4.
4
If compression and injector tests pass, check for intake manifold leaks at cylinder 4 using a smoke machine — any smoke escaping around the manifold gasket or port indicates a vacuum leak.
5
Use a borescope to visually inspect cylinder 4 combustion chamber through the glow plug or spark plug hole — look for excessive carbon, scored cylinder walls, or valve damage.
Estimated Repair Cost
$150 - $1,500
Parts + labor, varies by vehicle and location
This code indicates a cylinder 4 contribution or balance fault, with the ECM detecting that cylinder 4 is producing less power than the other cylinders. In some ECM implementations, P0273 specifically denotes the low-contribution side of the balance test for cylinder 4. The driver will experience ro...
The most common cause of P0273 (Cylinder 4 Contribution/Balance Fault) is: Cylinder 4 fuel injector with degraded performance — restricted or worn
Typical repair costs for P0273 range from $150 to $1,500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Moderate-risk drivability issue. The vehicle can be driven at reduced load for short distances. Prolonged operation risks catalytic converter or turbocharger damage from elevated exhaust temperatures on the affected bank.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0273 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel Injection / Engine Mechanical
Difficulty
Type
Generic (SAE)
Recommended Tools
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