P0273 Cylinder 5 fuel injector circuit reads low voltage

Injector 5 circuit low / cylinder 5 injector circuit low

Severity not verified — if the car runs badly, have it inspected

No source here rates the urgency of an injector circuit fault, so the class is not verified. One cylinder may get no fuel, so the engine can run rough or lose power.

It gets more serious if:

  • Inspect soon: Inspect soon if the engine stalls, loses power or misfires badly. The Ford 6.0 diesel complaint that lists this code describes stalling and the engine stopping while driving.

Source: how we rate severity

P0273 in short

P0273 means the engine computer found the cylinder 5 fuel injector circuit reading low voltage. A faulty injector, damaged wiring or a loose or corroded connector are the usual causes. Rough running, power loss or stalling means have it checked soon; a steady light alone can wait a short while.

The computer drives each fuel injector through its own circuit and checks the voltage on it. P0273 is the code for cylinder 5: the voltage stayed lower than the computer expects.

A bad injector coil, a broken or shorted wire, or a connector that is loose or corroded can all pull the voltage down. On some engines a separate injector driver module sits between the computer and the injectors, and a fault there is also possible. The computer itself is the least likely cause.

Because the code names a single cylinder, the check starts at that injector and its connector.

Most likely causes

These are general causes for this code across vehicles. None is specific to one make or model.

  1. Faulty injector on cylinder 5

    Common general cause
    Why it ranks here
    TroubleCodes.net lists a faulty injector first among the causes.
    What would change this
    Rises if the injector does not click or its coil reading is out of range. Falls if it clicks and tests like the others.
    How to test the fuel injector

  2. Open, short or loose or corroded connector in the injector circuit

    Common general cause
    Why it ranks here
    The same reference lists open circuits, shorts and corroded connectors, and the check list begins with the connector and harness.
    What would change this
    Rises if the connector is loose, green or wet or the harness is damaged. Falls if the wiring tests good.

  3. Injector driver or control module, or the engine computer

    Possible — needs testing
    Why it ranks here
    Listed as less common causes by TroubleCodes.net; check only after the injector and wiring pass.
    What would change this
    Rises if power reaches the injector but the driver does not switch it. Falls if the circuit and injector are at fault.
    How to test the engine control module (ecm / pcm)

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. With the engine off, look at the cylinder 5 injector connector and wiring for looseness, corrosion or damage.

    Low risk

  2. Have the injector listened to with the engine running, and compare it with the others.

    Best left to a shopTool: stethoscope

    Warning:The engine is running with belts and fans next to the injectors. A shop should do this.

  3. Check for power at the injector connector and whether the engine computer switches the other side.

    Best left to a shopTool: multimeter

    Warning:Injector circuits can carry high voltage on some diesels; back-probe with the right meter or leave it to a shop.

Symptoms

  • Check engine light with rough idle or misfire
  • Loss of power under acceleration
  • Stalling or engine stopping while driving Gets more serious: stop and have it checked.

Compare with: Car shaking with the check engine light on

How to fix

  1. With the engine off and cool, check that the injector connector for that cylinder is fully seated and free of corrosion.

Parts and cost context

  • Fuel injector:Test the injector and wiring before replacing; labor varies, get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

We don't have reviewed vehicle-specific evidence for P0273 yet. The causes and tests above apply across vehicles.

No curated relationships for P0273 yet.

All Fuel pump and injectors codes

Sources and review

  1. NHTSA complaint ODI 10446404 — NHTSA Office of Defects Investigation
  2. P0273 Injector 5 Circuit Low — TroubleCodes.net
  3. On-Board Diagnostic Trouble Codes (generic code title list) — Delaware Division of Motor Vehicles
  4. NHTSA complaint ODI 10320360 — NHTSA Office of Defects Investigation
Last reviewed
Written by
Saurabh K.
Editorial review
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Technician review
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