Powertrain, generic (extended)

P2248 O2 Sensor Reference Voltage Performance (Bank 2 Sensor 1)

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P2248 is meant for a reference voltage signal on the bank 2 upstream wide-band sensor that is present but implausible, as opposed to an open or shorted line. No manufacturer documents P2248 publicly, and the published diagnostic tables of Ford, GM, Saab and VW cover the bank 2 Nernst-cell line only with the open-circuit code P2247, while Ford routes shorts to P0151/P0152. A drifting reading usually stems from an aged or poisoned sensor element or extra resistance in the circuit, which Bosch's 300-ohm nominal cell value makes measurable. CARB requires upstream sensors to be monitored for out-of-range and implausible output. P2244 is the bank 1 counterpart, P2247 the open line, P2249/P2250 low/high. Mixture control on bank 2 becomes less accurate.

Likely causes

Aged or contaminated wide-band sensor on bank 2
High resistance in the reference voltage wire or connector
Exhaust leak ahead of the bank 2 sensor

Symptoms

  • Check engine light
  • Slightly higher fuel consumption
  • Possible failed emissions test

Repair estimate

DifficultyMediumDIY possible
Parts and labour€80–400
Time0.5–2 h

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

Parts involved

oxygen sensor bank2 sensor1oxygen sensor wiringecm

Related codes

P2244P2247P2249P2250P223DP0153

References: law.cornell.edu, bosch-motorsport.com, newtonnet.co.uk.