Powertrain, generic (extended)

P2594 Turbocharger Speed Sensor B Circuit Range/Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P2594 means the second turbocharger speed sensor produces a signal, but its reported speed does not agree with what the engine computer predicts for that turbo. Bentley documents it on the W12 in the Continental GT/GTC, Flying Spur and Bentayga (bulletin 2053348, versions 5 and 10): after a smoke test of intake and exhaust, a detached divider inside the air filter box on Continental and Flying Spur turned out to be one cause; with symptom code 23179 alone the code is cleared and retested without parts, while symptom code 32790 leads to a new speed sensor. P2593 and P2595-P2597 are circuit faults of the same sensor, P2579 the matching fault on sensor A. The warning lamp comes on.

Likely causes

Speed sensor B delivering an implausible signal
Detached divider in the air filter box disturbing the flow to one turbo
Intake or exhaust leak on the bank of the second turbo

Symptoms

  • Malfunction indicator lamp on
  • Fault often appears only under particular load or gradient conditions
  • Turbo speeds of both banks differ noticeably in live data

Repair estimate

DifficultyHardWorkshop job
Parts and labour€0–1,200
Time0.5–8 h

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

Parts involved

turbo speed sensor bturbocharger

Related codes

P2593P2595P2596P2597P2579

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