P26A8

What it means

The bypass valve A position sensor signal jumps or drops out intermittently. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.

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

• Sensor connector not fully seated

  high

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

• Harness chafed near thermostat housing

  medium

  A plausible cause — test and verify before replacing parts.

• Connector with intermittent contact under vibration

  low

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

Related help

• Full P26A8 diagnosis, causes & costs
• How to read check engine light codes
• Is it safe to drive with the light on?