Ageing or contaminated oxygen sensor on Bank 2, Sensor 3 giving a slow response; Exhaust leak near the sensor letting in outside air and distorting readings; Damaged, corroded or loose wiring or connector to the sensor; Sensor heater circuit fault slowing the sensor's warm-up and response; Underlying fuel mixture or engine fault on Bank 2, such as a vacuum leak or injector problem, upsetting the mixture; Contamination of the sensor by oil, coolant or silicone from an engine or sealant issue; Faulty control unit or outdated software calibration (only where the manufacturer has documented this).

P019D

O2 Sensor Delayed Response - Lean to Rich Bank 2 Sensor 3.

Generic
Powertrain
Generic code
Low severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
1: AreaFuel and air metering
9D: FaultThe specific fault in that area

What it means

P019D is the generic code for an oxygen sensor delayed response from lean to rich on Bank 2, Sensor 3. The control unit monitors how quickly this sensor's signal switches when the mixture changes from lean to rich, and it saw a response slower than the calibrated limit. Sensor 3 is a further downstream sensor, and its position depends on the exhaust layout of the particular model and engine.

Symptoms

Engine warning light on
Usually no noticeable change in driving
Possible slight rise in fuel consumption
Other oxygen sensor or catalyst codes stored alongside
Failed emissions test or readiness monitors not completing

Possible causes

Ageing or contaminated oxygen sensor on Bank 2, Sensor 3 giving a slow responselikely
Exhaust leak near the sensor letting in outside air and distorting readingslikely
Damaged, corroded or loose wiring or connector to the sensorpossible
Sensor heater circuit fault slowing the sensor's warm-up and responsepossible
Underlying fuel mixture or engine fault on Bank 2, such as a vacuum leak or injector problem, upsetting the mixturepossible
Contamination of the sensor by oil, coolant or silicone from an engine or sealant issuerare
Faulty control unit or outdated software calibration (only where the manufacturer has documented this)rare

How to diagnose

Read all stored and pending codes and the freeze frame data, noting engine load, temperature and fuel trims when the fault set
Check for related codes on other sensors or for misfire, fuel trim or catalyst faults, and deal with those first
Inspect the sensor wiring and connector for chafing, heat damage, corrosion and water ingress
Look and listen for exhaust leaks between the engine and the sensor, including flanges and joints
Confirm which physical sensor is Bank 2, Sensor 3 on this model using the manufacturer's layout information
Check the sensor heater circuit resistance and supply against the manufacturer's specification
Watch the live sensor signal during a steady drive and compare its switching speed with the other sensors
Check long and short term fuel trims on Bank 2 for signs of a vacuum leak or fuelling fault

How to fix

Repair any exhaust leak and replace damaged gaskets or sections
Repair or replace damaged wiring, terminals or the connector
Replace the Bank 2, Sensor 3 oxygen sensor if its response is confirmed slow or its heater is faulty
Fix any underlying mixture fault, such as a vacuum leak or faulty injector, found on Bank 2
Trace and cure the source of any contamination before fitting a new sensor
Apply a manufacturer software update only if a bulletin confirms a calibration issue for this model

Can I keep driving?

Low severity

The car can normally be driven while you arrange a repair, as this fault rarely affects drivability. Do not leave it for long, as an underlying mixture or exhaust problem could affect emissions and the catalyst.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.