P0273 code: Cylinder 5 Injector Circuit Low
P0273 means cylinder 5 Injector Circuit Low. The code says where to look, not what failed — the fix depends on which cause your car actually has.
What P0273 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.
P0273 symptoms
- 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 P0273
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 →
How to fix P0273
Advanced — usually a shop job unless you’re well equipped
- Confirm where cylinder 5 is and how hard it is to reach
This code only applies to engines with five or more cylinders. On inline fives and sixes, cylinder 5 is toward the firewall end; on a transverse V6 it depends on the maker's cylinder numbering, and when it is on the rear bank it is often under the intake plenum; V8 numbering depends on the manufacturer. Knowing this first decides how much testing you can do before anything comes apart.
- See whether its bank-mates are flagged too
If cylinder 5's low code arrives alongside codes for other injectors on the same bank, the shared harness branch or an intermediate connector serving that bank is a more likely common link than injector 5 itself. A lone P0273, perhaps with P0205 or P0305, keeps the focus on this one circuit.
- Back-probe the injector 5 pin at the module
On a port-injected engine at idle, back-probe the module's injector 5 pin with a meter. Because the injector is closed most of the time, a healthy circuit averages near battery voltage; a reading close to zero suggests a grounded wire or missing feed, while a normal reading with the code still setting points toward a winding that draws too much current.
- Measure through the harness before removing the plenum
Battery and module disconnected, measure from the module's injector 5 pin to the injector feed (for example the load side of the injector fuse, fuse pulled), then repeat for an easy-to-reach cylinder. A clearly lower reading for cylinder 5 indicates a shorted coil; also test that pin to ground, where any continuity means a chafed wire in the rear loom.
- Replace injector 5 with the intake off
If the injector is the culprit, relieve fuel pressure, remove the upper intake as the service manual describes, and replace injector 5 with fresh seals. New plenum gaskets and the specified bolt torque sequence are part of the job; reusing old gaskets invites a vacuum leak and a fresh set of codes.
DIY or shop? The through-harness measurement lets a careful DIYer separate wiring from injector without disassembly, and that alone narrows the job considerably. The repair itself is often the hard part: on many V6 layouts cylinder 5's injector and harness sit under the plenum, which means gaskets, sensor connectors, vacuum lines and a torque sequence. If you haven't taken an intake off before, this is a reasonable point to hand the confirmed diagnosis to a shop.
Tools for the DIY steps: Digital multimeter with fine back-probe leads · Wiring diagram for your engine · Socket set with long extensions · Torque wrench · Upper intake gasket set · Injector seal kit
Not sure which step applies to your car? Get the likely cause for your exact vehicle before buying anything for P0273.
Start a case with P0273 and your car. Redline weighs these causes against what your car shows, and names the check that would settle it before you buy parts.
Can I drive with P0273?
Redline can’t determine from a symptom or code alone whether your car is safe to drive.
P0273: common questions
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?
Redline can't settle that from the code alone, 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.
Related trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P0273 from your phone. See our guide to the best OBD2 Bluetooth adapters. Run a repair shop? See Redline for shops.
Generic OBD-II reference. Manufacturer-specific behavior varies. Confirm with a scan tool and, for safety-related codes, a professional inspection. Cost ranges are reference ranges, not quotes.
Seeing P0273 on your car?
Every problem becomes a Case. Tell Redline what the car is doing: it shows what the evidence supports, what’s still missing, and what to check next, before you approve a repair.
“Inner pad ~1 mm. Outer pad 3 mm.”
Next: check the slide pins move freely before buying parts.