P014CO2 Sensor Slow Response - Rich to Lean Bank 1 Sensor 1
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- The upstream oxygen sensor (sensor 1, before the catalytic converter) is the main control sensor for the air-fuel mixture. '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. Manufacturer documentation was found only for diesels: GM evaluates the oxygen signal of the NOx sensor when the engine goes from load to overrun and fails it above about 1.1 s (two trips); Ram lists it as soot-related. GM petrol engines use P015A/P015B instead, and Ford reported upstream response faults as P0133 in 2012. 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
- Slightly higher consumption or rough idle possible
- Higher emissions, possible emissions test failure
- Often no noticeable symptoms
- Likely causes
- LikelyUpstream oxygen sensor aged or poisoned (silicone, oil, coolant, soot)
- PossibleExhaust leak ahead of the sensor (manifold, flange)
- RareMixture fault: intake air leak, injectors, fuel pressure, air flow sensor
- RareSensor heater weak, sensor too cold
- RareConnector, wiring or control module software
- 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: €80 – €300
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.