P23D1

What it means

Per-cylinder fuel heaters (used on some heavy-duty diesels for cold-start atomisation) on cylinder 1 have an open control circuit.

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

• Open in heater or wiring

  high

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

• Pin pushed back out of connector body

  low

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

• Cracked solder joint inside the module or sensor

  low

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

Related help

• Full P23D1 diagnosis, causes & costs
• How to read check engine light codes
• Is it safe to drive with the light on?