Engine-Codes - Generic - P1143

P1143 - Heated Oxygen Sensor 1 Lean Shift Monitoring Bank 1

Repair Importance Level: 3/3
Repair Difficulty Level: 2/3  What is this?
Table of contents

P1143 Possible Causes

  • Faulty Front Heated Oxygen Sensor Bank 1
  • Intake air leaks
  • Front Heated Oxygen Sensor Bank 1 harness is open or shorted
  • Front Heated Oxygen Sensor Bank 1 circuit poor electrical connection
  • Fuel pressure
  • Injectors

How is the P1143 code repair?

Start by checking the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.

What is the cost to diagnose the P1143 code

Labor: 1.0

The cost to diagnose the P1143 code is 1.0 hour of labor. The auto repair labor rates vary widely across the country, and even within the same city. Most auto repairs shops charge between $75 and $150 per hour.
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Possible Symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)

P1143 Meaning

The Heated Oxygen Sensor 1 is placed into the front tube. It detects the amount of oxygen in the exhaust gas compared to the outside air. The heated oxygen sensor 1 has a closed-end tube made of ceramic zirconia. The zirconia generates voltage from approximately 1V in richer conditions to 0V in leaner conditions. The heated oxygen sensor 1 signal is sent to the Engine Control Module (ECM). The ECM adjusts the injection pulse duration to achieve the ideal air-fuel ratio. The ideal air-fuel ratio occurs near the radical change from 1V to 0V.

More Information

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Information for specific makes

  • P1143 AUDI Load Calculation Cross Check Upper Limit Exceeded
  • P1143 BUICK HO2S Bank 1 Sensor 3 Lean Or Low Voltage
  • P1143 CADILLAC HO2S Bank 1 Sensor 3 Lean Or Low Voltage
  • P1143 CHEVROLET HO2S Bank 1 Sensor 3 Lean System or Low Voltage
  • P1143 CHRYSLER Fuel Rail Pressure Malfunction Positive Pressure Deviation
  • P1143 DODGE Fuel Rail Pressure Malfunction Positive Pressure Deviation
  • P1143 GMC HO2S Bank 1 Sensor 3 Lean System or Low Voltage
  • P1143 INFINITI Heated Oxygen Sensor 1 Lean Shift Monitoring Bank 1
  • P1143 JEEP Fuel Rail Pressure Malfunction Positive Pressure Deviation
  • P1143 NISSAN Heated Oxygen Sensor 1 Lean Shift Monitoring Bank 1
  • P1143 SUBARU Pressure Sensor Circuit Low Input
  • P1143 VOLKSWAGEN Load Calculation Cross Check Upper Limit Exceeded

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