P2161 OBD-II Trouble Code: Vehicle Speed Sensor B Intermittent/Erratic

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P2161 trouble code definition

Vehicle Speed Sensor B Intermittent/Erratic

What the P2161 code means

P2161 is an OBD-II generic code for the engine control module (ECM) detecting the vehicle speed sensor 2 or B giving an intermittent or erratic voltage output.

What causes the P2161 code?

The engine control module is getting a voltage return from the vehicle speed sensor 2 or B that does not correspond with the speed sensor 1 or A. The sensor may not be giving a steady voltage increase or decrease with speed and may be jumping around indicating a problem.

What are the symptoms of the P2161 code?

  • The Check Engine Light will be illuminated and the code is set in ECM memory as a fault.

  • The transmission and transfer case will have shift issues or shift timing issues.

How does a mechanic diagnose the P2161 code?

  • Scans and documents the code in the ECM to check the freeze frame data for failure

  • Drives the vehicle to confirm the output speed of the speed sensors and compares the data

  • Diagnoses and repairs codes P2161 by looking at the scan data of the speed sensor to see if it is sending the same speed signal as sensor A or 1

  • Checks the sensor for damage to the sensor itself or wiring

Common mistakes when diagnosing the P2161 code

  • Clearing ECM memory codes before checking the freeze frame data for the main failure problem, so the failure may be duplicated and repaired

  • Failing to clear the ECM codes after the codes are fixed

  • Failing to check the sensor reluctor ring for damage before replacing the sensor

How serious is the P2161 code?

Code P2161 is an indication that the ECM detects one of the two speed sensors needed to shift the transmission and transfer case properly is not working as needed and may cause transmission shifting problems.

What repairs can fix the P2161 code?

  • Replacing the speed sensor B or 2
  • Repairing an open or short in the sensor return wiring or connector
  • Replacing a broken sensor reluctor

Additional comments for consideration regarding the P2161 code

Code P2161 is for a second speed sensor and is in the transfer case on some vehicles to determine the transfer case gear speeds.

Need help with a P2161 code?

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