P0273 medium Severity

P0273: Cylinder 5 Injector Circuit Low

May cause rough idle, decreased performance, misfire, and increased emissions

Overview

P0273 generic OBD‑II code indicating low voltage or circuit issue at the fuel injector for cylinder 5, causing misfires or imbalance in fuel delivery

Common Symptoms

  • Check Engine Light illuminated
  • Rough or uneven idle
  • Loss of power or hesitation
  • Decreased fuel economy
  • Possible misfire on cylinder 5

Most Common Causes

Faulty fuel injector on cylinder 5 high

Injector may fail electrically or mechanically and not supply adequate fuel

Wiring harness open or short to injector 5 circuit high

Frayed, broken, or shorted wiring can cause low voltage at the injector

Corroded or loose injector connector medium

Poor connection increases resistance, reducing voltage

PCM/ECM driver failure for injector 5 medium

Internal control driver in module may not provide proper voltage

Low injector circuit supply voltage medium

Low supply from relay/fuse or battery circuit can trigger code

Diagnostic Steps

  1. Use a quality OBD‑II scanner to verify code and check for related codes (e.g., P0305)
    Expected: P0273 stored; companion misfire codes may be present
    Interpretation: Confirms code presence and checks for related misfire conditions
  2. Visually inspect wiring harness and connectors at cylinder 5 injector
    Expected: No broken, corroded, or loose terminals
    Interpretation: If issues found, repair and retest
  3. Measure voltage at injector 5 with ignition on, engine off
    Expected: Nominal voltage (typically ~11.5–12.5V)
    Interpretation: Low voltage indicates wiring/supply issue
  4. Test injector resistance and activation (with proper tools)
    Expected: Resistance within manufacturer spec and clicking activation
    Interpretation: Out‑of‑spec or no activation indicates injector or PCM driver issue
  5. If wiring and injector are good, test PCM injector driver output
    Expected: Correct pulsed signal to injector
    Interpretation: No or weak signal suggests PCM internal driver fault

Repair Solutions

Replace faulty fuel injector on cylinder 5 medium
Estimated Cost: $150 - $500

Costs vary widely by vehicle make/model

Repair or replace damaged wiring and connectors medium
Estimated Cost: $80 - $200

Usually labor‑intensive if harness needs replacement

Replace PCM/ECM injector driver (if internal failure) hard
Estimated Cost: $800 - $1500

Requires programming and may necessitate professional service

Common Misdiagnoses

Avoid these common diagnostic mistakes:

  • Assuming general misfire without isolating specific injector or wiring fault

Frequently Asked Questions

What does a P0273 diagnostic trouble code signify?

The P0273 code stands for Cylinder 5 Injector Circuit Low. This generally indicates an issue with the Fuel System system.

Is it safe to drive with a P0273 code?

With a severity level of medium, may cause rough idle, decreased performance, misfire, and increased emissions

Common signs of the P0273 error code

The most typical signs are: Check Engine Light illuminated, Rough or uneven idle, Loss of power or hesitation.

What parts fail when P0273 is set?

The most common causes are: Faulty fuel injector on cylinder 5, Wiring harness open or short to injector 5 circuit, Corroded or loose injector connector.

Estimated repair costs for different causes of P0273

Expect to pay around $200 if the issue is a Repair or replace damaged wiring and connectors, but up to $1500 if the Replace PCM/ECM injector driver (if internal failure) needs replacement.

What cars are affected by the P0273 code?

This is a universal code. You might see P0273 on Ford, Chevrolet, Toyota, Honda, Nissan, or any other OBD-II vehicle.

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