P0274 – Cylinder 5 Injector Circuit High

P0274 is an OBD-II trouble code that points to a problem with the fuel injector circuit on cylinder 5, usually an electrical or injector performance issue. When this code sets, your engine control unit (ECU) sees the injector for that cylinder drawing too much current or staying open longer than it should. You might notice rough running, poor fuel economy, or a flashing check engine light. If you handle it quickly, the fix is usually straightforward. Ignore it, and you risk engine damage and a much bigger repair bill.

What Does P0274 Mean?

P0274 stands for “Cylinder 5 Injector Circuit High.” In simple terms, the ECU has detected that the injector circuit for cylinder 5 is operating at a higher than expected voltage or current. That usually means the injector is shorted internally, the wiring is damaged, or there’s a control issue on the ECU side.

This code is specific to cylinder 5, so it helps narrow down your diagnosis. It’s part of a family of injector circuit codes (P0261–P0296 range) that all deal with individual cylinders. While the engine may still run, it’s not running correctly, and continued driving can wash down cylinder walls with fuel and damage the catalytic converter.

Quick Reference

• Code: P0274 – Cylinder 5 Injector Circuit High
• Severity: Moderate to high – fix as soon as possible
• Common Causes: Bad injector, wiring short, connector corrosion
• Typical Symptoms: Misfire, rough idle, poor fuel economy, check engine light
• Primary Fixes: Replace injector, repair wiring, clean/repair connector

Real-World Example / Field Notes

In the shop, I see P0274 most often on higher-mileage trucks and SUVs that tow or see a lot of stop-and-go driving. One recent case was a V8 pickup with a rough idle, strong fuel smell, and a flashing check engine light under load. Scan data showed cylinder 5 misfiring heavily with P0274 stored. A quick injector balance test and a noid light check confirmed the injector was stuck partly open and drawing too much current. Replacing the injector and cleaning the connector fixed the issue, and fuel trims returned to normal on a short road test.

Symptoms of P0274

• Check engine light on or flashing – P0274 usually appears with a steady or flashing MIL, sometimes along with misfire codes.
• Rough idle – The engine may shake or feel uneven, especially at stoplights or in park.
• Loss of power – You may notice sluggish acceleration or hesitation when you step on the gas.
• Poor fuel economy – A stuck or over-fueling injector can cause a noticeable drop in MPG.
• Fuel smell from exhaust – Excess fuel in cylinder 5 can cause a rich exhaust odor or even light black smoke.
• Engine misfire – You might feel a stumble under load, and the ECU may log a cylinder 5 misfire code.
• Hard starting – In more severe cases, extra fuel can cause extended crank or rough start when cold.

Common Causes of P0274

Most Common Causes

• Faulty fuel injector (cylinder 5) – Internal short, coil failure, or mechanical sticking can cause high circuit current and trigger P0274.
• Damaged wiring harness – Chafed, melted, or pinched wires to injector 5 can short to power or ground and alter circuit voltage.
• Corroded or loose injector connector – Moisture, oil, or vibration can damage the terminals and cause erratic current draw.
• Poor electrical ground – A weak or shared ground point can affect injector operation and make the ECU see abnormal readings.

Less Common Causes

• ECU/PCM driver failure – The internal injector driver circuit in the ECU can fail and overdrive the injector, though this is relatively rare.
• Aftermarket tuning or modifications – Incorrect injector scaling, performance injectors, or poor tuning can confuse the ECU’s current monitoring.
• Contaminated fuel or debris – Debris can cause an injector to stick, leading to abnormal current and over-fueling.
• Previous engine work errors – Pinched harnesses, misrouted wires, or damaged connectors after head, intake, or injector work.

Diagnosis: Step-by-Step Guide

To properly diagnose P0274, you’ll want at least a good scan tool (preferably with live data and Mode $06), a digital multimeter, and basic hand tools. A noid light or injector tester, and sometimes an oscilloscope, can make the job much easier, but they’re not mandatory for a basic DIY check.

1. Confirm the code and check for companions
   Connect a scan tool, read all stored and pending codes, and note any misfire or fuel trim codes (like P0305). Clear the codes and see if P0274 returns quickly.
2. Inspect cylinder numbering
   Verify which cylinder is number 5 for your engine layout (varies by manufacturer). Many DIY mistakes happen from testing the wrong injector.
3. Visual inspection of injector 5 and harness
   With the engine off, inspect the injector body, connector, and nearby harness. Look for broken clips, oil saturation, melted insulation, or rubbed-through wires.
4. Check connector condition
   Unplug the injector 5 connector. Look for bent pins, green corrosion, moisture, or loose terminals. Clean with electrical contact cleaner and ensure a snug fit.
5. Measure injector resistance
   Using a multimeter, measure resistance across injector 5 terminals and compare it to spec and to other injectors. A significantly lower resistance often indicates an internal short.
6. Swap injectors (if accessible)
   If resistance looks normal but you still suspect the injector, swap injector 5 with another cylinder. Clear codes and see if P0274 (or misfire) moves to the new cylinder. If it does, the injector is the culprit.
7. Check power and ground at the connector
   With key on/engine off, verify that injector 5 has proper power and ground using a test light or multimeter. Compare readings with a known-good injector on another cylinder.
8. Check injector control signal
   Use a noid light or scope to verify the ECU is pulsing the injector correctly. An abnormal or constant-on signal may point to an ECU driver issue or a shorted wire.
9. Review live data and Mode $06
   Look at misfire counters, fuel trims, and cylinder contribution data. Mode $06 can show misfire counts for cylinder 5 even if a misfire code hasn’t set yet.
10. Perform a wiggle test
    With the engine idling, gently move the harness around injector 5. If the engine stumbles or the injector signal drops out, you’ve likely found a wiring fault.

Pro tip: When you find a bad injector on a high-mileage engine, consider replacing the full bank (or all injectors) if the budget allows. It helps keep fuel delivery balanced and can prevent future injector-related codes.

Possible Fixes & Repair Costs

Fixing P0274 usually means addressing an injector or wiring problem on cylinder 5. Costs vary by vehicle, engine design, and labor rates, but here are typical ranges and what affects them.

• Replace cylinder 5 injector – Parts $80–$300 each (OEM vs aftermarket), labor $100–$300 depending on access. Some engines require intake manifold removal, which increases labor.
• Repair or replace wiring/connector – Simple splice or terminal repair can be $50–$200. A full harness section replacement may run $200–$600 or more.
• Clean and secure connectors – Often under $100 if no parts are needed, just cleaning and re-pinning.
• ECU/PCM replacement or repair – Rare, but when needed, expect $500–$1,500+ including programming.
• Related maintenance – New seals, intake gaskets, or fuel rail O-rings may be required when injectors are removed.

Overall, most P0274 repairs fall in the $200–$800 range at a typical shop, depending on how buried the injectors are and whether you’re replacing a single injector or multiple. Luxury and diesel applications can be higher.

Can I Still Drive With P0274?

You can usually drive a short distance with P0274, but it’s not a good idea to ignore it. If the injector is stuck open or the circuit is overdriving it, you’re dumping extra fuel into cylinder 5. That can wash the oil film off the cylinder walls, dilute engine oil, foul spark plugs, and overheat the catalytic converter. If the check engine light is flashing or the engine runs very rough, avoid driving and have the vehicle towed to prevent further damage.

What Happens If You Ignore P0274?

Ignoring P0274 can turn a relatively simple injector or wiring repair into a major engine or emissions problem. Long-term over-fueling on one cylinder can damage the piston rings, contaminate the engine oil, and melt or clog the catalytic converter. You’ll also deal with poor fuel economy and possible failed emissions tests. Addressing the code early almost always saves money in the long run.

Last updated: January 22, 2026

Vehicles Commonly Affected by P0274

P0274 can appear on any OBD-II equipped vehicle, but it’s more frequently seen on multi-cylinder engines where injectors are harder to access and wiring runs are longer. In the field, I often see this code on:

• Ford F-150, F-250, Expedition, Explorer with V6 and V8 engines
• GM/Chevrolet Silverado, Sierra, Tahoe, Suburban, and Camaro V8s
• Dodge/Ram trucks and SUVs with HEMI and other V8 engines
• Chrysler/Jeep SUVs and minivans with V6/V8 powertrains
• Some European and Asian brands with direct-injection setups, especially as mileage climbs

Even if your exact model isn’t listed, the diagnostic approach is very similar across most modern gasoline engines.