Brief Chirp Noise from Exhaust on Cold Start - Normal Characteristic - keywords engine idle O2 off oxygen rattle rear right sensor squeak tin tinny whistle

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

On rare occasions, a brief chirp noise may be heard during a cold idle for about 30 seconds after cold starting the engine. It will be found that the noise is coming from the exhaust system and upon closer inspection; it will be found that the noise is the worst around the Position 2 O2 Sensor. Since the noise only occurs for a brief period of time, it may be hard to isolate the noise as described above. However, the same noise can typically be induced when hot or cold by carefully brake torquing the engine around 1,500 RPM.

If the SI diagnostics do not isolate the cause of this noise, determine if the noise is coming from the exhaust system around the Position 2 O2 sensor as described above. If there are no exhaust leaks noted and the noise is isolated to the Position 2 O2 Sensor, this should be considered a characteristic of the vehicle, no repairs should be performed, and a product report should be submitted by following the procedure outlined in 02-00-89-002D.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.