P21ECCylinder 9 Injector B Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P21EC signals a low circuit state, usually a grounded wire or, depending on the maker, also a break, on the B injector of cylinder 9. It can only occur on an engine with at least nine cylinders and two injectors per cylinder. No manufacturer documents it publicly; GM's and Ford's lists stop at cylinder 8. The one such engine on record is Lamborghini's Huracán V10, which combines direct and multi-point injection; which of the two it calls B is not published. Its firing order alternates between cylinders 1 to 5 and 6 to 10, so cylinder 9 belongs to the second bank. CARB requires circuit monitoring of such output components. By analogy with GM's V8, a ground below about 0.5 Ohm on the switched-off low side would count. Open circuit: P21D7; high fault: P21ED.
- What you may notice
- Check engine light on
- Misfire or rough running on cylinder 9
- Mixture deviation on the bank of cylinder 9
- Likely causes
- LikelyCylinder 9 B injector wire shorted to ground
- PossibleBroken wire, if the maker reports opens under the low code
- PossibleInjector coil shorted to housing or open
- RareEngine control module output 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: €150 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.