P0134 Oxygen sensor ahead of catalytic converter P0136 Oxygen sensor after catalytic converter P0137 Oxygen sensor after catalytic converter P0138 Oxygen sensor after catalytic converter
Okay, these are OBD-II trouble codes related specifically to issues with the **Downstream Oxygen Sensors** in your vehicle's exhaust system. Here's a breakdown of each code you mentioned: ### P0134: Oxygen Sensor (O2) Sensor Circuit Malfunction - Bank 1 * **Code:** P0134 * **Location:** Upstream sensor, located *before* the catalytic converter in one or more exhaust pipes. * **Function:** This is part of a system that monitors oxygen levels in the exhaust gases coming *into* the catalytic converter (the first sensor). * **What it means:** The PCM detected an error with the signal from the O2 sensor located upstream. This could be due to: * A faulty sensor itself. * Wiring issues connecting this sensor. * An exhaust leak between the upstream sensor and the catalytic converter (this is a very common cause for multiple P013x codes). ### P0136, 137, and P0138: Oxygen...