I have 2000 Jaguar XJ8 x308

I had a code P1647 so I purchased and replaced wideband upper oxygen sensor with Bosch one. I reset the error code but it came back with the same number. Any ideas?

:-(

 

Hi banar,

Here is the listing for P1647 from the Jaguar DTC Summaries guide:




As you can see from the list of possible causes, sensor failure is listed last. The more likely causes are problems with the electrical circuit. You can test for most of these problems with a basic voltmeter/ohmmeter.

I'm sure you identified the correct HO2S, but just in case, here's the diagram showing which set of cylinders is Bank 2:




Cheers,

Don

 

Don,
Thank you very much. I do have a multimeter, could you point me to a tutorial or video tutorial (even better) on how to test things you mentioned?

 

To test I would suggest a bit of common sense, like take a reading from one O2 sensor that works and check the faulty side, then trace back for a signal or use the search function to get readings your after. Using OEM parts on these cars means no drama. Fully understanding which O2 sensor you need to replace also carrying out a hard reset after fitting a part can help clear things up.

 

Did you replace the drivers side upstream or passenger? Bank 2 is drivers u.s. Iirc pins 1&3 are the heater, should have continuity. Other than this its wiring or the driver in the ecu

 

Hi banar,

Unfortunately, I am unaware of a tutorial for conducting tests on the HO2S electrical circuits. The best aid is the Electrical Guide, which contains schematics for the circuits and helpful bits such as Control Module Pin Out Information (see pdf page 49) that gives voltages or ground conductivity when certain pins are active. You can download the manual here:

Jaguar XJ Electrical Guide 2000

With your meter set to a low resistance range (200 ohms is common), you can check for conductivity and resistance between the conductors at the HO2S harness electrical connector, and check to see if any conductor is shorted to ground (the braided shield should be connected to ground).

Figure 4.1 on pdf page 101 shows the first Engine Management System schematic with the HO2S sensor wires identified by color (see the color codes near the front of the manual; for example, U=Blue).

Note that the sensors labeled B are the ones for Bank 2.

With the engine running and your meter set to an appropriate voltage range, you can check for the proper supply voltages.

Since high resistance in the circuit is one possible cause of P1647, it would be worth cleaning the electrical connectors at the ECM and at the HO2S in case water or humidity has caused some corrosion to form on the terminals. I use a small brass-bristled brush and zero-residue electrical contact cleaner (which is different from electric parts cleaner). CRC is a popular brand.

Cheers,

Don

 

All
Mine came in at about 106k miles after my battery failed. After doing all the stuff to get things back to normal with a new battery, the 1647 code appeared just when I thought I had all the issues sorted associated with a failed battery.

A quick check was to swap the connectors at the connection block from Left to Right and the code moved from 1647 to 1646 and back again when restored to normal locations.

After a close examination of the sensor side pins and wires to the sensor, that quick connection swap verified the sensor was indeed bad and not the wiring.

Fortunately the ECU is 18 inches away from the sensor connectors so checking the harness for continuity is really no problem, maybe 15 minutes.

 

How to test a O2 with a multimeter....Part 1 -How to Test the Front Oxygen Sensor With a Multimeter (2.2L GM)