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P173B – BMW DTC

BMW DTC P173B – CAN Engine Coolant Temperature Invalid

DTC P173B meaning on BMW

The Diagnostic Trouble Code (DTC) P173B for BMW indicates an issue with the Engine Coolant Temperature (ECT) sensor data being invalid on the Controller Area Network (CAN) bus. This means that the engine control module is receiving incorrect or implausible signals regarding the engine coolant temperature.

BMW DTC P173B symptoms

Symptoms associated with the BMW DTC P173B may include:

  • Check Engine Light (CEL) illuminated on the dashboard
  • Engine running hotter or colder than normal
  • Potential decrease in engine performance
  • Issues with the vehicle’s heating or cooling systems

BMW DTC P173B causes

Common causes of the BMW DTC P173B include:

  • Defective Engine Coolant Temperature (ECT) sensor
  • Faulty wiring or connections related to the ECT sensor
  • Issues with the Engine Control Module (ECM)
  • Interference or communication problems on the Controller Area Network (CAN) bus

BMW DTC P173B seriousness

The seriousness of the BMW DTC P173B code lies in the potential impact on engine performance and overall vehicle operation. Ignoring this issue can lead to inefficient engine operation, potential overheating, and other related problems. It is advisable to address this code promptly to prevent further damage.

How to diagnose DTC P173B on BMW

To diagnose the DTC P173B on a BMW, you can follow these steps:

  1. Use a diagnostic scanner to retrieve the fault codes stored in the Engine Control Module (ECM)
  2. Check the ECT sensor and its wiring for any visible damage or corrosion
  3. Perform a resistance test on the ECT sensor to verify its functionality
  4. Inspect the CAN bus connections for any loose or damaged wires
  5. Check for any related technical service bulletins (TSBs) from BMW

How to fix DTC P173B on BMW

To fix the DTC P173B on a BMW, you can consider the following actions:

  • Replace the Engine Coolant Temperature (ECT) sensor if it is found to be faulty
  • Repair or replace any damaged wiring or connections related to the ECT sensor
  • Reset the fault codes using a diagnostic scanner after making the necessary repairs
  • Perform a test drive to ensure the issue has been resolved

How to erase DTC P173B on BMW

To erase the DTC P173B on a BMW, you can use a diagnostic scanner to clear the fault codes stored in the Engine Control Module (ECM). Follow these steps:

  1. Connect the diagnostic scanner to the vehicle’s OBD-II port
  2. Select the option to erase fault codes from the ECM
  3. Confirm the action and wait for the scanner to complete the process
  4. Disconnect the scanner and start the vehicle to ensure the code has been successfully cleared

Recommended tools & DTC Scanners for BMW

Best Diagnostic App for modern BMWs: BimmerLink

Recommended Bluetooth adapter for Bimmerlink: OBDLink CX

Cable adapter for Bimmerlink: Enet Cable USB Type C

For older BMWs we recommend: Autel AutoLink AL319 (2024 version)

Easy-to-use Multimeter for reliable diagnostics: AstroAI Auto-ranging Multimeter

← All BMW Diagnostic Trouble Codes

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