P218DThrottle/Fuel Inhibit B Circuit Low
- 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
- P218D reports that the voltage on inhibit line B sits below the lowest permitted value, which normally points to a short to ground, a missing supply from the sending unit or an open line pulled down by the input stage. No manufacturer documents P218D publicly. For the A line, GM's 2005 table for the 3.5-litre V6 (L66) gives a concrete limit: P2554 is set when the analogue throttle inhibit circuit reads under 0.498 V for 4 seconds, with the check running after ignition off and the MIL lit on the next drive cycle. California's OBD rule requires out-of-range checks on such inputs. Chafed insulation touching body ground, water in a connector or a failed driver in the sending module are the likely causes. P218E is the opposite fault, P218B the general circuit code.
- What you may notice
- Check engine lamp on the following drive
- Possible power reduction
- Likely causes
- LikelyInhibit B wire shorted to ground
- PossibleWater or corrosion in a connector of the inhibit line
- RareOutput stage of the sending module failed
- 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.