P218CThrottle/Fuel Inhibit B Circuit Range/Performance
- 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
- P218C means the inhibit B line is electrically within limits, yet its state or response does not fit what the controller expects: it may signal a lock when none is requested, or fail to react during a function test. No manufacturer documents P218C publicly. GM's 2005 table for the 3.5-litre V6 (L66) shows the analogous test on line A as P2553: a function check of the relay path, judged by a normal signal on the serial data link with battery voltage above 7 V, run once per drive cycle after ignition off and lighting the MIL on the next drive. California's OBD rule asks for plausibility checks of such inputs. Likely causes are a sticking relay, a slow-switching driver or software mismatch between the modules. P218D/P218E cover hard low and high faults.
- What you may notice
- Check engine lamp on the next drive
- Occasional power reduction without obvious reason
- Likely causes
- PossibleRelay in the inhibit path sticking or switching late
- PossibleSoftware versions of the communicating modules do not match
- PossibleIntermittent contact causing implausible line states
- 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: €50 – €700
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.