P064D

What it means

An internal self-test in the control module reports a fault in its processing of the "oxygen sensor processing, bank 1" value. The module computes and cross-checks this value redundantly inside its own processor; when the results disagree, the code sets. It points to a hardware or software fault inside the module itself, not to a defect of the external sensor. Causes are an internal processor or memory fault, corrupted control-module software, or low or disturbed module supply voltage.

Is it safe to drive?

The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical.

Most likely causes

• Internal software anomaly

  high

  One of the most commonly reported causes for this code — check this first.

• Module software outdated, reflash may resolve

  low

  Less common, but worth ruling out after the more likely causes.

• Supply voltage outside specification

  low

  Less common, but worth ruling out after the more likely causes.

Related help

• Full P064D diagnosis, causes & costs
• How to read check engine light codes
• Is it safe to drive with the light on?