P123D BMW – Nitrogen Oxide Sensor Binary Lambda Signal Too Rich Poisoning Sensor

BMW Error Code P123D: Causes, Symptoms, and Repair

Meaning of Code P123D

Error code P123D indicates a problem related to the nitrogen oxide (NOx) sensor on a BMW vehicle. The engine control module (ECM) monitors this sensor and records this code if its values do not meet factory specifications.

Possible Causes of Code P123D

The main causes of this malfunction are:

  1. Faulty nitrogen oxide (NOx) sensor
  2. Faulty linear oxygen sensor
  3. Open or shorted linear oxygen sensor wiring harness
  4. Poor electrical connection of the linear oxygen sensor

Possible Symptoms

  • Check engine light on (or “Service Engine Soon” light)
  • Possible engine performance issues (depending on the sensor’s impact on the air-fuel mixture)

How to Repair Code P123D on a BMW?

1. Visual Inspection of Wiring and Connectors

  • Inspect the cables and connectors of the NOx sensor and the linear oxygen sensor.
  • Look for damaged wires, broken, bent, pushed, or corroded connectors.

2. NOx Sensor Testing

  • Use an OBDII diagnostic tool to monitor the sensor values.
  • Compare them to factory specifications.
  • If the values are abnormal, replace the NOx sensor.

3. Linear Oxygen Sensor Check

  • Test the sensor signal with a multimeter.
  • Check if the sensor sends consistent data to the ECM.
  • Replace it if necessary.

4. Electrical Wiring Check

  • Measure the wire continuity between the sensors and the ECM.
  • Repair or replace any damaged, cut, or shorted wiring.

5. Clearing the Code and Road Test

  • Once repairs are completed, clear the error code with an OBDII scanner.
  • Perform a road test to check if the code reappears.

Conclusion

Code P123D BMW is typically caused by a faulty NOx sensor or an electrical issue in its circuit. A thorough inspection and OBDII diagnostic are necessary to identify the exact source of the problem. If basic repairs do not resolve the error, it is advisable to consult a qualified BMW technician.

P123E – Nitrogen Oxide Sensor Poisoning Signal for NOx Too Low

P123E Possible Causes

  • Faulty nitrogen oxide (NOx) sensor
  • Nitrogen oxide (NOx) sensor harness is open or shorted
  • Poor electrical connection in the nitrogen oxide (NOx) sensor circuit

How is code P123E repaired?

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

Possible Symptoms

  • Check Engine Light on (or Service Engine Soon warning light)

P123E Meaning

The Engine Control Module (ECM) monitors the nitrogen oxide sensor. The ECM sets the OBDII code when the nitrogen oxide sensor does not meet factory specifications.

P123E BMW – Nitrogen Oxide Sensor Poisoning NOx Signal Too Low

P123E BMW Possible Causes

  • Faulty nitrogen oxide (NOx) sensor
  • Nitrogen oxide (NOx) sensor harness is open or shorted
  • Poor electrical connection in the nitrogen oxide (NOx) circuit

How is BMW P123E Code Repair Performed?

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

Possible Symptoms

  • Engine light on (or service engine soon warning light)

P123E BMW Meaning

The Engine Control Module (ECM) monitors the nitrogen oxide sensor. The ECM sets the OBDII code when the nitrogen oxide sensor does not meet factory specifications.

P1240 – Open Cylinder 4 Injector Circuit

P1240 Possible Causes

  • Faulty fuel injector 4
  • Fuel injector 4 harness is open or shorted
  • Poor electrical connection in fuel injector 4 circuit

How is code P1240 repaired?

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

Possible Symptoms

  • Engine light on (or service engine soon warning light)

P1240 Meaning

Injector Circuit Open Cylinder 4 is the generic description for code P1240, but the manufacturer may have a different description for your vehicle model and year. Currently, we have no further information about the P1240 OBDII code.

P1240 AUDI – Open Cylinder 4 Injector Circuit

P1240 AUDI Possible Causes

  • Faulty fuel injector 4
  • Fuel injector 4 harness is open or shorted
  • Poor electrical connection in fuel injector 4 circuit

How is code P1240 AUDI repaired?

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

Possible Symptoms

  • Engine light on (or service engine soon warning light)

P1240 AUDI Meaning

Injector Circuit Open Cylinder 4 is the generic description for Audi P1240 code, but the manufacturer may have a different description for your vehicle model and year. Currently, we have no further information about the Audi P1240 OBDII code.

P1240 BUICK – Cylinder 7 Injector Circuit Intermittent

P1240 BUICK Possible Causes

  • Faulty fuel injector 7
  • Fuel injector 7 harness is open or shorted
  • Poor electrical connection in fuel injector 7 circuit

How is the P1240 BUICK code repaired?

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

Possible Symptoms

  • Engine light on (or service engine soon warning light)

P1240 BUICK Meaning

Injector Circuit Cylinder 7 Intermittent is the generic description for Buick P1240 code, but the manufacturer may have a different description for your vehicle model and year. Currently, we have no further information about the Buick P1240 OBDII code.

P1240 CADILLAC – Cylinder 7 Injector Circuit Intermittent

P1240 CADILLAC Possible Causes

  • Faulty fuel injector 7
  • Fuel injector 7 harness is open or shorted
  • Poor electrical connection in fuel injector 7 circuit

How is the P1240 CADILLAC code repair performed?

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

Possible Symptoms

  • Engine light on (or service engine soon warning light)

P1240 CADILLAC Meaning

Injector Circuit Cylinder 7 Intermittent is the generic description for Cadillac P1240 code, but the manufacturer may have a different description for your vehicle model and year. Currently, we have no further information about the Cadillac P1240 OBDII code.

P1240 CHEVROLET – Cylinder 7 Injector Circuit Intermittent

P1240 CHEVROLET Possible Causes

  • Faulty fuel injector 7
  • Fuel injector 7 harness is open or shorted
  • Poor electrical connection in fuel injector 7 circuit

How is the P1240 CHEVROLET code repaired?

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

Possible Symptoms

  • Engine light on (or service engine soon warning light)

P1240 CHEVROLET Meaning

Injector Circuit Cylinder 7 Intermittent is the generic description for Chevrolet code P1240, but the manufacturer may have a different description for your vehicle model and year. Currently, we have no further information about the OBDII P1240 Chevrolet code.

P1240 GMC – Cylinder 7 Injector Circuit Intermittent

P1240 GMC Possible Causes

  • Faulty fuel injector 7
  • Fuel injector 7 harness is open or shorted
  • Poor electrical connection in fuel injector 7 circuit

How is GMC P1240 Code Repair Done?

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

Possible Symptoms

  • Engine light on (or service engine soon warning light)

P1240 GMC Meaning

Injector Circuit Cylinder 7 Intermittent is the generic description for GMC P1240 code, but the manufacturer may have a different description for your vehicle model and year. Currently, we have no further information about the GMC P1240 OBDII code.

P1240 ISUZU – High Fuel Pressure Regulator Circuit Open

P1240 ISUZU Possible Causes

  • Faulty high-pressure fuel regulator
  • High-pressure fuel regulator wiring harness is open or short-circuited
  • Poor electrical connection in the high-pressure fuel regulator circuit

How is the P1240 ISUZU code repaired?

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

Possible Symptoms

  • Check engine light on (or service engine soon warning light)

P1240 ISUZU Meaning

High-pressure fuel regulator circuit open is the generic description for the P1240 Isuzu code, but the manufacturer may have a different description for your vehicle model and year. Currently, we have no further information about the P1240 Isuzu OBDII code.