P2440

What it means

The switching/check valve in the secondary air injection plumbing on bank 1 is stuck in the open position. With the valve permanently open, exhaust gas can back-feed into the air pump and corrode it, while the downstream O2 sensor sees ambient air constantly.

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

• Switching valve stuck open by carbon or corrosion

  high

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

• Carbon or debris buildup preventing free movement

  low

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

• Component wear with age - mechanical play

  low

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

Related help

• Full P2440 diagnosis, causes & costs
• How to read check engine light codes
• Is it safe to drive with the light on?