P218BThrottle/Fuel Inhibit B Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P218B is a general electrical fault in the second throttle/fuel inhibit line, B. An inhibit line carries a signal with which another unit can tell the engine computer to keep the throttle closed or stop fuelling. No manufacturer documents the B line publicly. The only published use of this function concerns the A line: GM's 2005 table for the 3.5-litre V6 (L66) places it in the throttle valve control section, where the injection and throttle processors check each other, and monitors it with P2553-P2555 once per drive cycle after ignition off, lighting the MIL on the next drive cycle. California's OBD rule requires inputs of this kind to be checked for circuit faults. Open wires, corroded pins and module connector faults come first; reduced power is possible.
- What you may notice
- Check engine lamp on the following drive
- Possible power limitation
- Likely causes
- LikelyOpen or high-resistance inhibit B wire
- PossibleCorroded or loose pins at the engine or throttle module connector
- RareFault in the unit that drives the inhibit signal
- 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: €50 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.