P021A: Cylinder 7 Injection Timing

What does P021A mean?

P021A reports a fault in the injection timing of cylinder 7 on a diesel engine. Unlike P01D7/P01D8 ('over retarded/advanced', the result of the injector learning routine in overrun), this code has no direction, and what it checks is up to the manufacturer. GM uses it as an electrical check on the 6.6 litre L5P Duramax V8: at every injection the engine module measures how long the injector current takes to reach its pull-in level of 13 A. If on the V8 that time is outside 60–150 µs in 10 of 20 samples, the code sets and the warning light comes on in the first trip. For 2020–2021 Silverado/Sierra HD, GM issued a software update against false setting. FCA's V6 and Ford do not use it.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Check engine light on
• Rough running or misfire, rough idle
• Loss of power, smoke or knocking possible

Common causes

• High Injector of cylinder 7 faulty (coil, armature, wear, deposits)
• Medium Injector wiring or connector: contact resistance, corrosion, chafing
• Medium Engine software sets the code falsely (update available for some models)
• Low Injector driver stage or boost voltage in the engine module
• Low Wrong injector code, contaminated fuel or loose injector clamp

Likelihood is a general estimate across vehicles; your make and model may differ.