Powertrain, generic (extended)

P2A8F Alternative Fuel Pump B Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P2A8F applies to a second alternative fuel pump whose output has fallen short of expectations. Layouts with two pumps usually give each LNG vessel its own pump, a redundancy Westport's documents mention explicitly. In US20080302111A1, a selector valve decides which pump delivers, and once the controller judges one pump degraded it can switch to the other. The difficulty lies in telling a weak pump from an empty tank: Westport's US8726785B2 notes that little drive work per stroke can mean either a nearly empty vessel or a broken component such as the drive shaft. A P2A8F shortly after refuelling therefore points to the pump itself. Pump B may also be the healthy one, so check which tank was active. No manufacturer documents P2A8F or how its letter is assigned.

Likely causes

Worn seals reducing the delivery of pump B
Tank served by pump B almost empty, mimicking a weak pump
Broken drive shaft or coupling between hydraulic drive and pump B

Symptoms

  • Malfunction lamp on
  • Usable range shorter, fuel left in one tank
  • System changes to the other tank earlier than usual

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€800–6,000
Time3–10 h

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

Parts involved

alt fuel pump balt fuel filter

Related codes

P2A8EP2A90P2A83P2A84

References: law.cornell.edu, patents.google.com, patents.google.com.