P21E0: Cylinder 3 Injector B Circuit Low

What does P21E0 mean?

P21E0 reports a low circuit state on the B injector of cylinder 3. Mitsubishi lists it for the 2022 Eclipse Cross as the direct injector code and does not use the open code P21D1, so an interrupted wire and a short to ground both end up here once they last 2 s. Its procedure measures the injector across its two DI terminals at the intermediate connector, then the harness on both sides of that connector, and only then suspects the ECM. Port injector faults on the same cylinder are P0267 and P0268. On GM's 2019 LT5 V8 cylinder 3 is the second cylinder on the left bank; its supplemental injector fails this test with less than 0.5 Ohm between low side and ground in 20 of 25 samples while the driver is off, Type A in one trip. Expect a cylinder 3 misfire; P21E1 is the high fault.

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

Symptoms

• Check engine light on
• Misfire on cylinder 3 (P0303)
• Rough idle

Common causes

• High Cylinder 3 injector wire broken or shorted to ground
• Medium Injector of cylinder 3 with open or shorted coil
• Low Engine control module output faulty

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