P2C18B Camshaft Profile Actuator Position Sensor B Circuit Low Bank 1
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- A ground short in the position sensor B line on the bank 1 exhaust side sets P2C18. On GM's L3B this is the feedback wire of exhaust actuator 2. GM's table phrases it as a fault of the sensor's solenoid driver: with the output commanded on, a signal-to-ground impedance not above 0.5 ohm in four samples out of five, supply over 11 V and ignition in crank or run, stores Type A and switches on the MIL (19OBDG03D, unchanged in 25OBDG03B). As with P2C14, GM's PIT5677 and 21-NA-149 list P2C18 only as a keyword, not under the codes found on affected trucks. Areas to inspect include the harness run over the camshaft carrier cover and below the air cleaner box, plus the actuator connector. The second exhaust actuator stays inactive until the short is repaired.
- What you may notice
- MIL comes on in the first trip
- Exhaust profile no longer changes, small rise in fuel use
- Likely causes
- LikelyHarness insulation damaged at the camshaft carrier cover or under the air cleaner housing
- PossibleExhaust actuator 2 shorted internally to ground
- RareWater or oil bridging contacts in the plug
- 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 – €900
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.