OBD-II trouble code
P0274: Cylinder 5 Injector Circuit High
The cylinder 5 injector control circuit measured high — an open circuit or a short to power. The number itself is the trap: cylinder 5 lands on opposite sides of the engine depending on whose numbering convention the manufacturer follows.
Quick facts
- System
- Powertrain
- Category
- Fuel Injectors
- Severity
- Medium severity
- Drivable
- No — stop driving until repaired
- Repair cost range
- $30 – $1,800
- DIY difficulty
- Intermediate DIY
Browse every code in P0200–P0299, or start from the full code library.
What does P0274 mean?
The existence of a cylinder 5 tells you something useful before the bonnet is even open. An engine with a fifth cylinder has at least five, which rules out the four-cylinder engines that make up most of the vehicle population and leaves inline fives, inline sixes, V6s, V8s and larger. Nearly all of those have two cylinder heads, two exhaust banks and two sets of fuel trims, and that architecture gives you diagnostic options a four-cylinder cannot offer — but it also introduces a trap that catches people on this exact code.
Cylinder 5 is the first cylinder number where the major numbering conventions physically disagree. Under one widely used scheme, cylinders 1 through 4 occupy one bank and 5 through 8 the other, which puts cylinder 5 at the front of the opposite head from cylinder 1. Under another equally common scheme the cylinders alternate side to side, so the odd numbers all sit on the same bank and cylinder 5 is the third cylinder back on the same side as cylinder 1. Same code, same number, opposite side of the engine. On a V8 this is the difference between removing the correct intake and removing the wrong one, and it is the reason that looking up the numbering for the specific engine is not boilerplate advice on this page — it is the first real step.
The good news is that a two-bank engine hands you a free way to confirm which side you should be on before touching a fastener. A dead cylinder dumps its full charge of air into the exhaust unburned, and the oxygen sensor on that bank reads it as lean, so the module adds fuel and the long-term trim for that bank climbs hard while the other bank stays close to normal. Read both banks' trims, see which one has run away, and you have established the affected side from the driver's seat. If both banks look normal, the cylinder is probably not as dead as the code implies and the fault may be confined to the monitoring circuit.
The electrical claim is the same one any injector circuit-high code makes: the module pulls the control wire to ground to fire the injector, it watches for the voltage to fall, and it did not. Either the path is broken — a severed wire, a corroded connector, an open coil winding — or something is feeding the wire with power and holding it up against the module. Two possibilities, and a continuity test plus a voltage test on the control wire with the module disconnected separates them.
What is genuinely specific to a multi-bank engine is the power feed. Injectors on six- and eight-cylinder engines are rarely fed individually. They are grouped, very often one group per bank, through a shared fuse and relay or a single feed wire that splices out to each injector on that side. Lose that feed and the module's control-side measurement goes abnormal on every injector in the group at once, setting high codes across several cylinders that no amount of injector replacement will fix. If this code arrived alongside high codes on the other cylinders that share its bank, stop testing injectors and go straight to the shared feed — one repair clears all of them.
The economics are the reverse of a four-cylinder's. On a transverse V6 the bank containing cylinder 5 is frequently the rear bank, tucked against the bulkhead under the upper intake manifold, and even reseating a connector there can mean an intake removal and a set of gaskets. On a longitudinal V8 the injector sits under the intake valley. Either way, the cheap physical tests that make sense on an inline four are not cheap here, and the sensible sequence is inverted: do as much electrical testing as possible from the module connector and the accessible end of the harness before committing to disassembly, because the labour to reach the part is often larger than the part.
With cylinder 5 out, expect a misfire code alongside this one, and expect the catalytic converter on that bank to be at risk from the unburned mixture passing through it. The vehicle should be driven only as far as it needs to go.
Common causes
- Loss of the switched power feed shared by the injectors on that bank — a blown fuse, a failed relay or a broken splice, which sets high codes on several cylinders at once
- Open circuit in the cylinder 5 injector control wire or a corroded splice within the bank harness
- Open coil winding inside the cylinder 5 injector
- Connector unlatched or a terminal backed out following intake manifold removal, which is when this connector is normally disturbed
- Control wire shorted to battery voltage or to another powered circuit
- Chafed harness contacting a powered stud or bracket in the intake valley
- Corrosion or coolant intrusion at a connector sitting in the valley of a V engine, where spilled coolant collects
- Failed cylinder 5 injector driver inside the module
Symptoms
- Check engine light on, sometimes flashing under load
- Dead or very weak cylinder 5 with a rough, uneven idle
- Misfire codes such as P0305, or P0300 if other cylinders on the same bank are also affected
- Long-term fuel trim running hard positive on one bank while the other bank stays close to normal
- Injector circuit codes on several cylinders of the same bank when a shared feed has failed
- Marked loss of power and hesitation
- Raw fuel odor from the exhaust and, over time, overheating of that bank's catalytic converter
- Hard starting or extended cranking
Diagnostic steps
- 1.Look up the cylinder numbering for this specific engine first. Cylinder 5 sits on the opposite bank from cylinder 1 under one common convention and on the same bank under another, and guessing can mean disassembling the wrong side of the engine.
- 2.Read both banks' long-term fuel trims before touching anything. The bank whose trim has run hard positive is the one with the dead cylinder, which confirms the side from the driver's seat.
- 3.Record every companion code. High codes on several cylinders of the same bank point at the shared power feed and not at any injector.
- 4.With the key on, check for battery voltage at two or three injector connectors on the affected bank. Missing at all of them means the fuse, relay or feed wire is the single fault to repair.
- 5.Do the electrical work you can reach before committing to disassembly. Disconnect the module connector and test the cylinder 5 control wire end to end for continuity, then check it for unexpected voltage.
- 6.Only then open up access to the injector itself, and take the opportunity to inspect the whole bank harness in the valley while it is exposed rather than making a second trip.
- 7.Unplug the injector and measure its coil resistance with the key off. An infinite reading confirms an open winding.
- 8.Inspect the connector for coolant residue and corrosion, since the valley of a V engine collects anything spilled during previous cooling system work.
- 9.Once wiring and injector both test correct, verify the module is actually pulsing the circuit with a noid light or a scan tool output test before considering the module.
Repair cost
$30 – $1,800
The two ends of this range are set by access rather than by severity. A blown fuse or failed injector relay is often under $100 and fixes every code on the bank at once, which is why it is checked first. Repairing a wire or terminal that can be reached is $75 to $250. The expensive case is the part being buried: a cylinder 5 injector on the rear bank of a transverse V6 or in the valley of a V8 typically needs the upper intake off, so $60 to $400 in parts arrives with 2 to 4 hours of labour and a gasket set, and diesel injectors commonly reach $400 to $900 installed. A failed injector driver inside the module runs $500 to $1,500 with programming. Diagnosis alone is $75 to $150 and is worth more here than on an easily accessed engine.
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DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.