Powertrain, generic · Fuel and air metering

P013F O2 Sensor Delayed Response - Lean to Rich Bank 1 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 lean-to-rich direction, tested when fuel returns or the control module briefly enriches the mixture. GM checks whether the signal rises above 350 mV before about 75 g of air have passed after the forced change; failing needs two trips. GM investigated this code together with its siblings on 2023–2024 Corvettes with non-original converters or exhaust parts. 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 bank1 sensor2exhaust systemcatalytic converter

Related codes

P013EP013BP014BP0139P2270P0420

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