OBD codes / P0273
P0273
ModerateCylinder 5 Injector Circuit Low
A faulted cylinder 5 injector circuit means unburned fuel can pass into the exhaust and overheat the catalytic converter. Gentle, limited driving is usually tolerable with a steady light, but prioritize the repair, and stop driving if the check-engine light flashes or the misfire becomes severe.
What this code means
On engines with five or more cylinders, the ECM monitors each injector's control circuit individually, and P0273 flags the cylinder 5 circuit for reading below expected voltage. The usual mechanisms are a short to ground in the wiring, an open circuit, or an injector coil that has shorted internally. This is a fault in the electrical path — a different animal from a mechanically clogged injector, which restricts fuel but leaves circuit voltage normal. The cylinder-specific callout makes diagnosis manageable: measure cylinder 5's injector resistance and inspect its wiring, using another cylinder as the reference. When the injector genuinely stops firing you'll typically also see P0205 (cylinder 5 injector circuit) or P0305 (cylinder 5 misfire). Cylinder 5's position varies with engine architecture — on many V6 and V8 layouts it's mid-bank — so check your engine's numbering diagram before digging in.
Symptoms you might notice
- Misfire or dropout on cylinder 5
- Rough idle and drivetrain vibration
- Weak or hesitant acceleration
- Check-engine light, which may flash during active misfire
- Possible silent storage of the code when the fault is intermittent
What it costs to fix
Typical range: $60–$450 · about ~0.5–2 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Fuel injector (single) | $50–$300 | ~0.5–2 hrs |
| Wiring/connector repair | $5–$50 | ~0.5–2 hrs |
Wiring repairs stay cheap; injectors cost more. Cylinder 5 often sits on the rear bank or under the intake on V-type engines, and direct-injection injectors are pricier — both push the total toward the high end.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0273 for my exact vehicle →
Frequently asked
What is P0273 telling me?
The ECM saw voltage below the expected range on the cylinder 5 injector's control circuit — evidence of a short to ground, damaged wiring, or an injector coil that has failed electrically. It is not a statement about fuel quality or a dirty injector.
How do I narrow it down to injector versus wiring?
A resistance check on the cylinder 5 injector is the quickest filter: a reading matching the other injectors points to the harness or connector, while a shorted or open reading points to the injector. Swapping injectors between cylinders and watching whether the code follows removes all doubt.
Is it okay to drive with P0273 for a while?
Short trips at light throttle are usually fine, but this isn't a code to sit on. A misfiring cylinder feeds raw fuel to the catalytic converter, and converter replacement costs far more than the injector or wiring fix. A flashing light means stop now.
Which cylinder is number 5 on my engine?
It depends on the manufacturer and layout — inline engines usually count front to back, while V-engines split numbering across the two banks in different orders. Check the cylinder-numbering diagram for your specific engine before replacing parts, or you may service the wrong cylinder.
Seeing P0273 on your car? Get a diagnosis specific to your exact year, make and model.
Diagnose P0273 for my vehicleRelated trouble codes
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Generic OBD-II reference. Manufacturer-specific behavior varies — confirm with a scan tool and, for safety-related codes, a professional inspection.