High Idle in 1998 Jeep Cherokee After OBD Code P0135 and Sensor Replacement
My 1998 Jeep Cherokee is experiencing high idle speed after replacing both the oxygen (O2) sensor and the throttle position sensor (TPS). The vehicle previously showed OBD code P0135, which I addressed during the repair. However, despite these changes, the engine now idles too high. Could the replacement of these sensors be causing or contributing to this issue? Is there a connection between P0135 and elevated idle speed? I suspect the TPS may be malfunctioning due to improper installation, or perhaps there is a vacuum leak after the throttle body. What are common causes for high idle in a 4.0L engine Jeep Cherokee post-sensor replacement?
Please list all diagnostic codes and describe when they appeared—did any new codes emerge after the sensor replacements? Why were these specific parts replaced? Assuming it's a 4.0L engine, this is a common setup. Without further details, the most likely cause is that the TPS is holding the throttle open—possibly due to improper installation. Alternatively, check for vacuum leaks downstream of the throttle body—how high is the idle speed? Note: P0135 typically indicates a wiring issue (e.g., faulty sensor connection or blown fuse), not directly related to high idle. Ensure you used an OEM-quality O2 sensor and TPS; aftermarket parts can cause intermittent faults.