Fuel and air

P0212 — Injector Circuit Malfunction, Cylinder 12

Severity: medium Drive with care, to a shop

What P0212 means

The engine control module drives each fuel injector individually, supplying power and switching the ground side to open the injector for a precise time. P0212 sets when the electrical readings of the cylinder 12 injector circuit are out of range, such as an open, a short or wrong resistance. As a result, that cylinder may get the wrong amount of fuel or none at all.

Symptoms

  • Check Engine light on
  • Rough idle
  • Misfire on cylinder 12
  • Reduced power and sluggish acceleration
  • Higher fuel consumption
  • Engine vibration under load

Possible causes

  1. Failed fuel injector on cylinder 12 (open or shorted coil)
  2. Open or shorted injector wiring harness
  3. Corroded or loose injector connector
  4. Poor power supply or ground in the injector circuit
  5. Failed injector driver inside the ECM
  6. Wiring damaged by heat or chafing

How to diagnose

  1. Read all codes and freeze frame data and look for related misfire codes
  2. Inspect the cylinder 12 injector connector and harness for damage, corrosion and chafing
  3. Measure injector coil resistance and compare it to specification
  4. Check for power and a control signal at the connector using a noid light or scope
  5. Test the wiring from injector to ECM for opens and shorts to ground or voltage
  6. Compare cylinder balance and fuel trims with a scan tool
  7. Check fuel pressure and rule out intake leaks
  8. If wiring and injector are good, test the ECM driver

Common fixes

  • Repair the wiring or replace a damaged connector
  • Replace the cylinder 12 fuel injector
  • Correct the power or ground supply problem in the circuit
  • Repair or replace the ECM if a driver fault is confirmed

Questions and answers

Can I drive with a P0212 code?

Only briefly and gently, for example to a repair shop. The misfire raises fuel use and can damage the catalytic converter, so don't put the repair off.

What most often causes P0212?

Most often it is the injector itself or a problem in its wiring or connector. A bad ECM is rare and is checked last.

Is clearing the code enough?

No. If the cause isn't fixed, the code will return. Clear it only after repairs and after confirming the cylinder runs properly.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.