Powertrain, generic (extended)

P2555 Throttle/Fuel Inhibit A Circuit High

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modePossible

P2555 indicates excess voltage on throttle/fuel inhibit circuit A. The same 2005 GM document for the L66 V6 uses two limits depending on key state: more than 10 V while the ignition is on, or more than 4.5 V once it is off, with the fault judged after 4 s. As with its sibling checks, monitoring happens after shutdown, a single time per drive cycle, and the lamp waits until the next trip. A line that should be at a low level reading close to system voltage hints at a short to a battery-fed wire, a relay stuck closed or a lost ground on the receiving side. P2554 is the low-voltage counterpart, P2553 the relay function check and P2552 the general circuit fault. CARB requires makers to monitor electronic inputs of this kind for out-of-range values. Effects can include limited throttle or reduced power.

Likely causes

Inhibit circuit shorted to a battery-fed wire

Inhibit relay stuck closed

Missing ground on the receiving side

Symptoms

Check engine light on the next trip
Limited throttle opening or reduced power

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€40–500

Time0.5–2.5 h

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

Parts involved

throttle inhibit awiring harness

Related codes

P2552 P2553 P2554

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