Powertrain, generic (extended)

P21D4 Cylinder 6 Injector B Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P21D4 is the last B injector code on a six-cylinder engine. Ford's second-generation 2.7 and 3.5 EcoBoost V6 combine port and direct injection, label the port injectors B and test this circuit together with P21CF to P21D3, continuously above 11 V within 5 s; on these engines cylinder 6 is the rear cylinder of the second bank. On the 3.5 the direct system is shut down at low speed and light load and the engine runs on port fuel alone, so an open cylinder 6 port injector is most noticeable at idle and in gentle driving. GM's 2019 LT5 V8 also covers cylinder 6 in its injection module, Type A after 20 of 25 failed samples. The A-side direct injector code is P0206, the misfire code P0306; P21E6 and P21E7 are the low and high faults.

Likely causes

Port injector of cylinder 6 open internally
Damaged wire at the rear of the engine, hard to inspect
Connector not fully latched after earlier work on the intake

Symptoms

  • Check engine light on
  • Misfire on cylinder 6 (P0306)
  • Slightly rough idle

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€100–700
Time1–3.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

fuel injectorinjector wiringengine control module

Related codes

P0206P21E6P21E7P21D3P21D5P0306

References: gsi.ext.gm.com, fordservicecontent.com, en.wikipedia.org.