Powertrain, generic (extended)

P2B8F Turbocharger/Supercharger B Temperature Sensor Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P2B8F is the general circuit fault for temperature sensor B, the second sensor of this kind on a charged engine, often belonging to a second turbocharger. Which spot it watches is left to the manufacturer, and none documents this code publicly. The engine computer sets it when the signal is lost or unusable without clearly sitting below or above its range, for example during short interruptions. Sensors near the exhaust side often use a platinum measuring resistor on a mineral-insulated lead, as Heraeus describes in patent US8328419B2, because ordinary NTC parts reach their limit at about 900 degrees Celsius. CARB 13 CCR 1968.2 (e)(15) requires circuit monitoring of such inputs. Out-of-range codes are P2B90 and P2B91; sensor A has P2B6E.

Likely causes

Loose or heat-damaged connector with intermittent contact
Wiring chafed or brittle near hot exhaust parts
Temperature sensor B failed internally

Symptoms

  • Warning lamp with stored code
  • Sensor B value missing or jumping in live data

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–450
Time0.5–2.5 h

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

Parts involved

turbocharger b temperature sensorwiring harnessecm

Related codes

P2B90P2B91P2B92P2B6EU0689

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