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P1682 – What Does It Mean and How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.


P1682 is an OBD-II Code that refers to Ignition 1 Switch Circuit 2


A P1682 code is a manufacturer specific diagnostic trouble code related to GM vehicles and similar makes that occurs when the ECM/PCM detects a problem with the ignition switch that is having a voltage problem. A faulty ignition switch is generally to blame. The ignition system consists of two “circuits.” The first one is sent to the ECM through the throttle actuator control. The ignition switch is the second circuit (the one under discussion) that passes through it.

If the ECM detects a problem with the ignition 1 switch circuit, it will set a P1682 code and turn on the check engine light.


Common causes for this code include:

  • Faulty ignition switch
  • Power relay might be faulty
  • Ignition switch harness is open or shorted
  • Ignition switch circuit poor electrical connection
  • The ECM might be Bad (rare)


The symptoms of a P1682 code are:

  • Illuminated Check Engine Light
  • Engine may not start


To diagnose a P1682 DTC code, a technician would:

  1. Scan for codes in the ECM and look at the freeze frame data for failure.
  2. Visually inspect all the wiring and connectors in the circuit.
  3. Inspect the ignition switch for signs of failure. 
  4. Check the power relay for signs of failure.
  5. Test the ECM for proper ground and voltage supply.

Common mistakes

The following are some of the most common mistakes that a technician may make when diagnosing a P1682 code:

  • Not thoroughly inspecting all the wiring and connectors for damage.
  • Failing to test the ECM for proper voltage and ground supply.
  • Replacing parts without first confirm they are faulty.

How serious is this?

A P1682 code is a fairly serious code because it can prevent the engine from starting.

What repairs can fix the code?

The following are solutions that may fix this problem:

  • Broken or faulty wirings must be repaired or replaced
  • Bad or damaged connectors must be replaced
  • Defective ignition switch must be replaced
  • Faulty ECM must be replaced

Related codes

A P1682 is related to and may be accompanied by the following codes:

P1681 – Ignition 1 Switch Circuit 1

P1683 – Ignition 1 Switch Circuit 3


In conclusion, the P1682 code is a diagnostic trouble code that refers to a problem with the ignition switch circuit. This code is fairly serious since it can prevent the engine from starting. The most common cause for this code is a faulty ignition switch, but it can also be caused by a power relay or an ignition switch harness that is open or shorted. If you have this code, it is important to have it diagnosed and repaired as soon as possible.