Having just replaced the air filter element in my 2001 X-Type 3.0 auto I thought I'd see what fault codes were present, completely expecting there to be none. To my surprise a Pending Fault P1647 was recorded for Bank 2. I see from previous posts on this forum that this refers to the oxygen sensors. Other than to remove the battery box cover so I could access and disconnect the electrical connector for the MAF sensor I haven't upset anything. I should have checked for fault codes before starting, maybe it was there already. I haven't previously noticed any issues in the way the car responds to throttle changes. The car with the new filter fitted idles and throttles up to 2500 rpm without issue but I haven't yet left the driveway so we'll see.

I'm running the Torque Pro app on my mobile phone via an ELM327 OBDII bluetooth connector. Initially the AFR was showing 0:1 but soon went back to 14.7:1. I have a lot of my trips saved with numerous sensor values recorded, any suggestions? My last trip showed values for the O2 Bank 2 sensor (v) of between 0.06 and 0.82. Are these usual values? What is a Pending Fault?

The car has nearly completed 100,000kms (160,000 miles), I got her with just 74,526kms just over 4 years ago in 2014. Just about all my driving is done within 10kms of home and in town. On the rare occasion I get onto a highway the car performs faultlessly with plenty of go for overtaking where required.

 

Well my Pending Fault has been fixed, however it is now replaced with a Current Fault P1647. So no real change I suppose but the car still seems to drive the same as always, unless it has something to do with my rear left wheel centre cap falling off. Today's trip returned O2 sensor values of 0.05-0.97 for Bank 1 and 0.05-0.94 for Bank 2. Looking back through my records from before I noticed this fault code the minor difference between the banks appears consistent. What does this fault mean? Do I need to have the engine running or turned off to clear fault codes on the X-Type?

 

P1647 indicates the Upstream sensor malfunction. The sensor has 2 circuits 1 is the heater circuit and 2 is the sensor circuit. Since you are still getting consistent output during operation, then most likely you have an open heater circuit.
You can clear the codes with the reader with the engine off. It will take a couple of drive cycles and if it is not an anomaly the code will return.
If you have to replace one at least this one is the easy one.

 

Chances are it's actually faulty.

If it is then the PCM is estimating fuel and will put too much in (to avoid the severe damage lean would cause) and will do gradual damage to the cat. conv.

Do not rely on the code coming back if you clear it!!

That's because you will also clear the OBD monitors and if they don't set again the PCM may be unable to flag codes.

Check the monitors have set in a short time if you do clear the codes.

The whole plan of OBD is NOT to clear codes until AFTER you have performed a fix.

 

Today I cleared the code and it came back almost immediately as a Pending Fault, the same as it first appeared. Is it possible I could have upset the wiring when I changed the air filter? I didn't remove the air box base or the air intakes to the air box. I did disconnect the MAF sensor connector.