P06C5Cylinder 1 Glow Plug Incorrect
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- A glow plug has no identification; the control unit recognises its type only from its electrical behaviour – cold resistance at switch-on and how resistance rises during heating (R = U/I). A Beru patent describes how steel and ceramic plugs are told apart this way so the right heating profile is used and a wrong or mixed type is reported. A low-voltage plug on an 11 V control burns out, an 11 V plug on a low-voltage control glows too weakly. GM uses 'incorrect' for any resistance outside the window: the 2025 diesels check 0.22–2.00 Ω (15 of 25 samples, two trips), the L5P glow module a ramp-dependent window. P06C5 reports this for cylinder 1. VW's 2.0 TDI (Jetta, Golf, Passat 2011–13) checks the type 2 s after ignition on – starting during that time caused false codes from the voltage dip, fixed with new glow module software.
- What you may notice
- Check engine and glow plug lamp
- Harder cold start or white smoke
- Possibly plug burnt out (low-voltage plug on 11 V control)
- Code after replacing plugs
- Likely causes
- LikelyWrong glow plug type fitted in cylinder 1 (steel/ceramic, voltage rating)
- PossiblePlug resistance drifted (ageing, damage)
- PossibleGlow module software or check during cranking (false report)
- RareContact resistance at the plug connector
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €40 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.