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P0043 - OBD Trouble Code

OBD Code P0043 HO2S Heater Control Circuit Low B1S3

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If you feel sudden drop in the engine performance and continuous stalling and hard idles along with flashing of check engine lights on the dashboard, this may be an indication of OBD Code P0043 being stored in the PCM/ECM.

 

P0043 stands for low circuit voltage for the heated oxygen sensor bank 1 sensor 3. This code can be seen with P0044 and P0042.

Learn More About OBD Error Code P0043

The definition of P0043 is low voltage for the heater control circuit. P0043 indicates that the car’s ECU has detected lower than expected voltage and has triggered a warning light.

 

PCM (Powertrain Control Module) takes inputs form Heated Oxygen Sensor to determine oxygen content in the exhaust system. Bank 1, sensor 3 refers to the third sensor back on bank 1. Bank 1 is the side of the engine that contains the #1 cylinder. This information is mainly used to monitor the performance of the catalytic converter which reduces the emissions on cold start-up. The PCM continuously monitors the heater circuits for abnormalities. The Oxygen sensor heater can be controlled in one of two ways depending on the make of the car. One way is that the PCM directly controls the voltage feed to the heater either directly or via a HO2S relay or would be a fused 12-volt battery that feeds to the heater element anytime the ignition is on and the control of the heater is done by a driver in the PCM. It’s important to find out which way is used to correctly diagnose this problem and to know as to why the Code P0043 is being set in the PCM.

 

What causes the problem of Heater Circuit Control Low (B1 S3)?

 

  • Failed Bank 1 Sensor 3
  • Short/open wiring problem
  • High resistance and poor electrical connections
  • ECU error

Replace/Repair These Parts To Fix OBD Code P0043

  1. Heated Oxygen Sensor - The inadequate heating of the oxygen sensor immediately makes the ECM to go into failsafe mode due to failure of the fuel delivery system, and engine control module. Replace faulty sensors immediately.
  2. Heated Oxygen Sensor Harness - OBD Error Code P0043 may also occur if the sensor harness is damaged leading improper fuel supply causing improper engine performance. It is advised the replace with the new one. Buy quality auto parts from us.
  3. Heated Oxygen Sensor Connector - A faulty Oxygen Sensor Connector can will not be able to read the correct volume of air entering the engine. Replace your old/damaged connectors now.
  4. Heater Circuit Fuse - Damaged Heater Circuit Fuse can result in improper or complete failure of the heater circuit. Visit us for quality fuses and parts.
  5. Engine Control Module - ECM faults can store and display wrong OBD Code which can result in wrong diagnosis. Thus, replace the damaged components now.
  6. Powertrain Control Module - PCM issues directly affects the engine control and transmission control module. Thus, replace faulty components now.
  7. Catalytic Converter - Sometimes catalytic converters can overheat and become faulty. Replace your old catalytic converter now!
  8. Diagnostic Tool - Find wide range of diagnostic tools to detect and correct the OBD code error.
  9. Exhaust System - Replace damaged exhaust parts immediately as a damaged one hampers the fuel economy and thus the performance.

Symptoms Of OBD Error Code P0043

If the Engine Control Unit detects low on the heater control circuit for bank1 sensor 3, it will immediately flash Check Engine Light on the dashboard. In rare cases, the car may also run poorly and see increased fuel consumption.

How To Correct P0043 HO2S Heater Control Circuit Low B1S3

  • Replace Bank 1 sensor 3
  • Repair/replace open or short in the wiring
  • Bank 1 Sensor 3 fuse replacement
  • Replacement of ECU

Easy Diagnosis Of Engine Error OBD Code P0043

  • Install a scan tool in vehicles OBD-II port to check if P0043 is present or not.
  • Freeze frame data and test drive to check if the code reappears under same conditions.
  • If the Check Engine Light returns upon test, then the code is confirmed.
  • Performs a visual inspection of wiring and bank 1 sensor 3 for any damage, breaks, or shorted wiring.
  • Check for the voltage of Bank 1 sensor 3 and make sure it is not excessively low. If low voltage is confirmed, bank 1 sensor 3 is faulty.
  • A diagnostic of the ECU will be performed, if the voltage is not low and sensors are fine.

 

Common mistakes when diagnosing the P0043 code

 

P0043 is an uncommon code and following all diagnostic steps is important so nothing is overlooked. Oxygen sensors should be properly examined and replaced, if faulty. Always confirm low voltage for oxygen sensor bank 1 sensor 3 before any replacement is performed and avoid going to the ECU straightaway.

Other Diagnostic Codes Related To OBD Code P0043

P0042 - HO2S Heater Control Circuit (Bank 1 Sensor 3)

P0044 - HO2S Heater Control Circuit High (Bank 1 Sensor 3)