P0273
UniversalCylinder 5 Injector Circuit Low
The engine computer has detected an abnormally low electrical signal in the fuel injector circuit for cylinder 5. The injector meters fuel into that cylinder when commanded; a circuit fault can interfere with its operation and cause poor running. This code identifies a detected condition, not proof that the injector itself needs replacement.
⚠️ Before You Begin (Safety First)
If the engine runs very rough, loses power, or the check-engine light flashes, stop driving when it is safe to do so and arrange prompt diagnosis. Continued driving with a severe misfire can damage the catalytic converter. If the vehicle runs normally, avoid hard driving and have the fault checked soon.
Common Symptoms
- The check-engine light may be on, even if the vehicle seems to run normally.
- A rough idle or engine misfire may occur if cylinder 5 does not receive the commanded fuel delivery.
- Hesitation, reduced power, or uneven acceleration may occur when the engine is misfiring.
- Fuel economy or exhaust emissions may worsen if combustion is incomplete.
- There may be no noticeable symptoms if the condition is intermittent or does not significantly affect injector operation.
Common Causes
- A short to ground or damaged insulation in the cylinder 5 injector wiring can pull the circuit signal low.
- A damaged, loose, or corroded injector connector can interfere with the electrical circuit.
- An electrical fault within the cylinder 5 injector can affect the circuit signal.
- A fault in the circuit's power supply or control wiring can produce an abnormal low signal.
- A fault in the engine computer's injector driver is possible, but should be considered only after the circuit and injector have been tested.
Diagnostic Steps
- Check for other stored codes and note when the problem occurs; related codes or operating conditions can help guide diagnosis.
- With the engine off, visually inspect the accessible cylinder 5 injector connector and wiring for looseness, corrosion, chafing, or visible damage. Cylinder locations vary by engine.
- Do not disconnect or probe electrical components with the circuit powered. If the connector or wiring is damaged, or the cause is not apparent, have a technician perform vehicle-specific circuit tests.
- After any repair, have the codes cleared and confirm that the fault does not return under appropriate operating conditions.
When to Call a Professional
A technician can use vehicle-specific wiring information and scan data to check the cylinder 5 injector circuit, its power and control paths, and the engine computer's driver operation. Electrical tests should distinguish a wiring or connector fault from an injector fault before parts are replaced.
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Commonly Asked Questions
Does P0273 prove that the cylinder 5 injector is bad?
No. It identifies a low electrical signal in the injector circuit. Wiring, the connector, the circuit's power or control path, and the injector itself may all need to be checked.
Can I keep driving with P0273?
If the vehicle runs smoothly, cautious short-term driving to arrange diagnosis may be possible. Stop when safe and seek prompt help if the engine runs very rough, loses power, or the check-engine light flashes.
What does the injector do?
The injector meters fuel into its cylinder when commanded by the engine computer. An electrical circuit problem can prevent it from operating as intended.
Is cylinder 5 in the same location on every vehicle?
No. Cylinder numbering and access depend on the engine. Use service information for the specific model, year, and engine before identifying components or testing the circuit.
Browse Available Code Guides
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