P21CFCylinder 1 Injector B Circuit/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P21CF flags an open drive circuit of the second injector on cylinder 1. Which of the two injectors is B depends on the maker: Ford gives the letter to the port injector and keeps A, coded P0201, for direct injection, whereas Mitsubishi calls its direct injectors B and files open circuits under the low code P21DB. Ford's 2020 to 2025 gasoline summaries test the B circuits continuously above 11 V and need 5 s. GM's 2019 LT5 V8 judges it in a separate injection module: over 200 kOhm on the switched-off low side in 20 of 25 samples, Type A with the MIL in the first trip. Ford bulletin SSM 49996 lists it with P21D0 and P21D1 on 2021 Bronco Sport 1.5 models with a harness damaged at the transmission. With direct injection still working, rough idle or P0301 is the usual sign.
- What you may notice
- Check engine light on
- Rough idle or misfire on cylinder 1, often with P0301
- Further harness codes stored at the same time
- Likely causes
- LikelyChafed or broken wire in the port injector harness (on the Bronco Sport near the transmission cover)
- PossibleOpen coil in the cylinder 1 port injector
- PossibleLoose or corroded plug at the injector
- RareFaulty driver stage in the engine module or separate injector module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.