Powertrain, generic (extended)

P2A68 Alternative Fuel Tank C Level Sensor Circuit Intermittent/Erratic

Check engine lightOn

EmissionsRelevant

Drive cycleRequired

Limp modeNo

The last code of this block covers a tank C level signal that flickers: it is valid most of the time but suffers short gaps or jumps unrelated to fuel movement. On vehicles with three tanks the wiring to tank C is often the longest and has the most joints, each a chance for a loose crimp or green corrosion; frame flex can open a fractured conductor for an instant. Where the level is computed from CNG pressure, a flickering pressure input (P2A4A) can be the real source. No manufacturer documents P2A68; it parallels P2A63 for tank B and P01B3 for tank A, and CARB treats erratic inputs as part of component monitoring. Stored freeze-frame values plus live level data on a test drive narrow it down.

Likely causes

Loose crimp or corroded joint in the long tank C harness

Conductor fractured, opening under frame flex

Unsteady tank C pressure input behind a calculated level (CNG)

Symptoms

Tank C level jumps on the display
Check engine light now and then
Range display unsteady

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€60–600

Time0.5–3 h

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

Parts involved

alt fuel tank c level sensorwiring harnessafcm

References: law.cornell.edu, static.nhtsa.gov.