P013AO2 Sensor Slow Response - Rich to Lean Bank 1 Sensor 2
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- The downstream oxygen sensor (sensor 2, after the catalytic converter) is used for fine mixture trim and to monitor the converter. 'Slow response' means the signal transition itself is too sluggish – it takes too long to pass between two voltage levels. This code covers the rich-to-lean direction, usually tested during deceleration fuel cut-off. GM forces the test itself and measures how quickly the signal passes from 450 to 150 mV relative to air flow; a filtered value above its limit sets the code after one trip (fallback: target not reached before about 60 g of air). Ford measures the slew rate during fuel cut-off, normalised to the converter's stored oxygen. Lexus traced one case to a leaking manifold gasket ahead of the sensor; on Ram diesels it is soot-related. CARB requires separate detection of slow and delayed faults in each direction (phased in from 2009 for downstream and 2011 for upstream sensors).
- What you may notice
- 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
- Likely causes
- LikelyDownstream oxygen sensor aged or contaminated (soot, oil, silicone, coolant)
- PossibleExhaust leak between manifold/turbo and the sensor
- RareConverter faulty or non-original with different oxygen storage
- RareControl module software too sensitive (update available)
- RareSensor connector or wiring with contact resistance
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €60 – €250
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.