P2553Throttle/Fuel Inhibit A 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
- P2553 means the throttle/fuel inhibit path A is electrically present but does not behave as commanded. GM's 2005 diagnostic table for the 3.5 L L66 engine files it under electronic throttle control and runs it as a function check of the inhibit relay over a serial data link: a healthy relay produces no serial data, so any data seen there counts as a failure. The test needs battery voltage above 7 V and the key off, and judges a fault within 0.2 s. Like the other inhibit checks in that table it runs once per driving cycle after the ignition is switched off, so the lamp comes on only during the following drive. In that table the throttle valve monitor also has two processors cross-checking each other. P2552 is the general circuit code, P2554 and P2555 voltage faults on the same line.
- What you may notice
- Check engine light on the drive after the fault was found
- Possible reduced power or throttle limp mode
- Likely causes
- LikelyInhibit relay sticking or contacts worn
- PossibleFault in the relay control or feedback wiring
- RareInternal fault in the engine or throttle control unit
- 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: €40 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.