P21E4Cylinder 5 Injector B Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P21E4 flags a low state on the circuit of the second (B) injector serving cylinder 5. The only public OBD summary that lists it is GM's for the 2019 Corvette ZR1, whose supercharged LT5 V8 pairs direct injectors with port injectors and drives the supplemental ones from a separate fuel injection control module (FICM). While that driver is off, a low side reading 0.5 Ohm or less toward ground in 20 of 25 samples, taken every 100 ms, is judged a short and becomes a Type A fault with the MIL in the first trip. On GM's V8 numbering cylinder 5 is the third cylinder of the left bank, i.e. bank 1. Because a grounded low side can let the injector flow uncommanded, a rich bank 1 may follow. Ford's dual-injection engines report B shorts on this cylinder only as P21D3.
- What you may notice
- Check engine light on
- Rich running or fuel trim pulled back on bank 1
- Rough idle or misfire on cylinder 5
- Likely causes
- LikelyLow-side wire of the cylinder 5 B injector touching ground
- PossibleInjector winding shorted to its housing
- PossibleMoisture or corrosion in the injector connector
- RareDriver stage in the injection control module faulty
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.