P20D4

What it means

Exhaust Aftertreatment Fuel Injector B Control Circuit High: the control-circuit voltage is above the expected range. This injector doses fuel into the exhaust to raise temperature for diesel particulate-filter regeneration; it does not fuel the engine.

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

• Short to B+

  high

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

• Connector pins corroded - high contact resistance

  low

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

• Supply wire pinched against B+ source

  low

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

Related help

• Full P20D4 diagnosis, causes & costs
• How to read check engine light codes
• Is it safe to drive with the light on?