What does it mean?
OBD II fault code P0153 is defined as “ O2 Sensor Circuit Slow Response (Bank 2 Sensor 1)”, and is set when the PCM (Powertrain Control Module) detects that Heated Oxygen Sensor #1 is not operating within predefined parameters.
Note that “Slow Response” in the definition refers to the time taken by the sensor to react to changes in the composition of the exhaust gas. “Oxygen Sensor 1” refers to the oxygen sensor upstream of the catalytic converter, and “Bank 2” refers to the bank of cylinders that does not contain cylinder #1. This distinction is only made on engines that have two cylinder heads.
Oxygen sensors with the #1 designation have the purpose of analysing the exhaust gas before it enters the catalytic converter.
In terms of operating principles, a #1 oxygen sensor measures the amount of oxygen in the exhaust stream, based on which it generates a signal voltage that is sent to, and used by the PCM to make adjustments to the fuel trim to ensure that the ideal ratio between air and fuel (14.7 parts of air to 1 part of fuel) is maintained at all times, and under all operating conditions.
In an engine that is in perfect mechanical condition, and on which there are no misfiring, lean-, or rich running conditions, vacuum and/or exhaust leaks, or other defects, a change in the throttle position produces an almost immediate change in the amount of oxygen in the exhaust stream.
The #1 oxygen sensor is designed to register this change near instantaneously by means of a change in the generated signal voltage; if this does not happen and the sensor takes longer than about 100 milliseconds to react after the PCM has entered closed loop operation, the PCM registers the slow reaction, stores a trouble code, and illuminates a warning light.
Unlike older narrow-band oxygen sensors, modern broadband heated oxygen sensors have the ability to control the air/fuel mixture right from the moment of start-up in sub-zero temperatures all the way to wide-open-throttle conditions in the hottest weather without significant lags in reaction times, which reduces emissions considerably. Note however that while response times vary between applications, the differences are not great.
Nevertheless, it is recommended that the manual for the application being worked on be consulted for the correct response time, and other values such as control circuit /sensor resistance and reference voltage. The panel of images below shows the most common types of fouling that can damage an oxygen sensor permanently. Oil fouling, which is not shown here, leaves a sticky, tarry residue on the sensor.
If fouling by silicone-based compounds is found, cease the use of all aftermarket oil and fuel additives immediately, since some aftermarket additives that contain silicone-derived compounds can eventually destroy catalytic converters as well.