P0291 medium Severity

P0291: Cylinder 11 Injector Circuit Low

Engine may run rough, reduced power and fuel economy; check engine light illuminated

Overview

P0291 indicates a low voltage condition in the fuel injector circuit for cylinder #11, often due to electrical or injector faults requiring targeted diagnostic of wiring and injector performance

Common Symptoms

  • Check engine light illuminated
  • Engine running rough
  • Reduced engine power
  • Decreased fuel economy

Most Common Causes

Faulty fuel injector on cylinder 11 high

Injector may be clogged or failed electrically

Open or short in fuel injector harness high

Wiring issues to injector can cause low circuit voltage

Loose or corroded fuel injector connector medium

Poor connection can result in low voltage reading

Issues with injector control module or PCM driving circuit low

Less common but possible control circuit faults

Diagnostic Steps

  1. Retrieve code and freeze frame data with OBD-II scanner
    Expected: P0291 present with relevant engine conditions
    Interpretation: Confirms code and context for when it set
  2. Visually inspect wiring and connector at cylinder 11 injector
    Expected: No damaged wires, corrosion, loose pins
    Interpretation: Damage or corrosion indicates likely cause
  3. Measure injector circuit voltage and resistance
    Expected: Circuit meets manufacturer specs
    Interpretation: Deviation indicates wiring/PCM/injector fault
  4. Swap injector 11 with another cylinder (if applicable)
    Expected: Code moves with injector if injector fault
    Interpretation: Confirms injector vs wiring harness issue

Repair Solutions

Repair or replace damaged injector wiring or connector medium
Estimated Cost: $50 - $250

Costs vary based on labor and extent of wiring repair

Clean or replace fuel injector on cylinder 11 medium
Estimated Cost: $150 - $600

Injector replacement more costly if high-performance or OEM part required

Inspect and repair PCM/injector control module circuits hard
Estimated Cost: $300 - $900

Advanced diagnostics or module replacement may be needed

Common Misdiagnoses

Avoid these common diagnostic mistakes:

  • Confusing P0291 with turbocharger/boost related codes (e.g., P0299)

Frequently Asked Questions

What does a P0291 diagnostic trouble code signify?

Technically, the P0291 code represents Cylinder 11 Injector Circuit Low. It usually points to a fault within the Fuel System.

Reflecting on severity: How bad is P0291?

This is a medium priority issue. Engine may run rough, reduced power and fuel economy; check engine light illuminated

What happens when the P0291 code is active?

You may experience the following: Check engine light illuminated, Engine running rough, Reduced engine power.

Potential causes for OBDII code P0291

The most common causes are: Faulty fuel injector on cylinder 11, Open or short in fuel injector harness, Loose or corroded fuel injector connector.

What is the price difference for fixing P0291?

Expect to pay around $250 if the issue is a Repair or replace damaged injector wiring or connector, but up to $900 if the Inspect and repair PCM/injector control module circuits needs replacement.

What cars are affected by the P0291 code?

The P0291 code is a generic powertrain code, meaning it applies to almost all makes and models, such as Honda, Toyota, VW, Ford, and Chevy.

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