Powertrain, generic · Fuel and air metering

P014A O2 Sensor Delayed Response - Rich to Lean Bank 2 Sensor 2

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

The downstream oxygen sensor (sensor 2, after the catalytic converter) is used for fine mixture trim and to monitor the converter. 'Delayed response' means the sensor starts reacting too late, or does not reach the target level at all, after the mixture has changed. This code covers the rich-to-lean direction, usually tested during deceleration fuel cut-off. Bank 2 only exists on V and boxer engines. GM checks whether the signal falls below 450 mV before about 45 g of air have passed after the forced change; failing needs two trips. Ford uses the same stuck-in-range test for bank 2, failing after three bad results in a row. CARB requires separate detection of slow and delayed faults in each direction (phased in from 2009 for downstream and 2011 for upstream sensors).

Likely causes

Downstream oxygen sensor aged or contaminated (soot, oil, silicone, coolant)
Exhaust leak between manifold/turbo and the sensor
Converter faulty or non-original with different oxygen storage
Control module software too sensitive (update available)
Sensor connector or wiring with contact resistance

Symptoms

  • Check engine light on
  • Usually no noticeable change in driving
  • Catalyst monitor may stay incomplete (inspection readiness missing)
  • With a converter cause, P0420/P0430 may follow

Repair estimate

DifficultyEasyDIY possible
Parts and labour€60–250
Time0.5–1.5 h

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

Parts involved

oxygen sensor bank2 sensor2exhaust systemcatalytic converter

Related codes

P014BP013CP013EP0159P2272P0430

References: law.cornell.edu, gsi.ext.gm.com, newtonnet.co.uk, static.nhtsa.gov.