Powertrain, generic (extended)

P2553 Throttle/Fuel Inhibit A Circuit Range/Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

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.

Likely causes

Inhibit relay sticking or contacts worn
Fault in the relay control or feedback wiring
Internal fault in the engine or throttle control unit

Symptoms

  • Check engine light on the drive after the fault was found
  • Possible reduced power or throttle limp mode

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€40–600
Time0.5–2.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

throttle inhibit arelay

Related codes

P2552P2554P2555P2108

References: gsi.ext.gm.com, law.cornell.edu.