My 2002 X-Type 2.5L has a P1646 error code. Just started last week.

From reading these posts (very helpful!), I believe I need to test and replace an oxygen sensor on bank 1.

3 Questions:

1) Is bank 1 on the radiator or firewall side of the engine?

2) Do I replace sensor 1 (exhaust manifold before catalytic converter) or sensor 2 (downstream of catalytic converter), or both?

3) Can I test the oxygen sensor to confirm it's the problem before replace it? How?

Some addition information:
1) Check engine light comes on and P1646 code appears only when I first start the engine. I can erase the P1646 code soon after starting the engine and the check engine light remains off for as long as I drive. The only new code I get is P1646 PD (PENDING). But when I stop and restart the engine, the check engine light turns on again with another P1646 error code.

2) 96K miles. Runs well with good gas mileage, ~29-31 mpg highway, ~23-25 mpg city.

Thanks,
dwclapp

 

Quick update after a visit to the Jag dealer. (Nobody has replied yet to my questions, but I figure at least to help other's with what I'm learning):

My 3 Questions were:

1) Is bank 1 the radiator or firewall side of the engine?
Answer: Bank 1 = firewall, Bank 2 = radiator.

2) Do I replace Sensor 1 (exhaust manifold before catalytic converter) or sensor 2 (downstream of cat converter), or both?
Answer: Probably Upstream Sensor 1 with a bad electric heating element. The dealer will know for certain next week using his code reader.

Unfortunately the most difficult sensor to reach is Bank 1, Sensor 1, so I'm told by the Jag dealer. It screws into the catalytic convert between the engine & firewall. The easier sensors to change are Bank 1, Sensor 2 - in the exhaust pipe below the catalytic converter, Bank 1, Sensor 1 - in the exhaust manifold between engine and radiator, Bank 1, Sensor 2 - in the catalytic converter between engine and radiator.

FYI, the Jag dealer quoted me $239.65 for Oxygen sensor part number is C2S38497 (aka C2S 38497) plus ~$480 labor = $700+. But I think that's the part number for the downstream (black plug) sensor. I think the part number for the upstream (grey plug) sensor is C2S51801 (aka C2S 51801).
3) Can I test the oxygen sensor to confirm it's the problem before replace it?
Can anyone tell me how to check the ohms of the heating element?

Thanks,
dwclapp

 

I : DTC P0131, P0132, P0133, P1646. RIGHT-HAND BANK HO2S


I1 : CHECK THE CONSTANT CIRCUIT OF THE RIGHT-HAND BANK HO2S FOR OPEN CIRCUIT

1. Disconnect the HO2S electrical connector EN37.
2. Disconnect the PCM electrical connector, EN16.
3. Measure the resistance between EN16, pin 84 (P) and EN37, pin 4 (P).

Is the resistance less than 5 ohms?

Yes Goto I2


No REPAIR the circuit. For additional information, refer to the wiring diagrams. CLEAR the DTCs. TEST the system for normal operation.


I2 : CHECK THE CONSTANT CIRCUIT OF THE RIGHT-HAND BANK HO2S FOR SHORT TO GROUND

1. Measure the resistance between EN16, pin 84 (P) and GROUND.

Is the resistance less than 10,000 ohms?

Yes REPAIR the short circuit. For additional information, refer to the wiring diagrams. CLEAR the DTCs. TEST the system for normal operation.


No Goto I3


I3 : CHECK THE CONSTANT CIRCUIT OF THE RIGHT-HAND BANK HO2S FOR SHORT TO BATTERY

1. Connect the PCM electrical connector EN16.
2. Turn the ignition switch to the ON position.
3. Measure the voltage between EN37, pin 4 (P) and GROUND.

Is the voltage greater than 5 volts?

Yes REPAIR the short circuit. For additional information, refer to the wiring diagrams. CLEAR the DTCs. TEST the system for normal operation.


No Goto I4


I4 : CHECK THE VARIABLE CIRCUIT OF THE RIGHT-HAND BANK HO2S FOR OPEN CIRCUIT

1. Disconnect the PCM electrical connector, EN16.
2. Measure the resistance between EN16, pin 83 (Y) and EN37, pin 3 (Y).

Is the resistance less than 5 ohms?

Yes Goto I5


No REPAIR the circuit. For additional information, refer to the wiring diagrams. CLEAR the DTCs. TEST the system for normal operation.


I5 : CHECK THE VARIABLE CIRCUIT OF THE RIGHT-HAND BANK HO2S FOR SHORT TO GROUND

1. Measure the resistance between EN16, pin 83 (Y) and GROUND.

Is the resistance less than 10,000 ohms?

Yes REPAIR the short circuit. For additional information, refer to the wiring diagrams. CLEAR the DTCs. TEST the system for normal operation.


No Goto I6


I6 : CHECK THE VARIABLE CIRCUIT OF THE RIGHT-HAND BANK HO2S FOR SHORT TO BATTERY

1. Connect the PCM electrical connector EN16.
2. Turn the ignition switch to the ON position.
3. Measure the voltage between EN37, pin 3 (Y) and GROUND.

Is the voltage greater than 5 volts?

Yes REPAIR the short circuit. For additional information, refer to the wiring diagrams. CLEAR the DTCs. TEST the system for normal operation.


No INSTALL a new HO2S. CLEAR the DTCs. TEST the system for normal operation. If the DTC is repeated, INSTALL a new PCM

 

Yvonne: Thank-you. This is very helpful. Do you have or can you point me to wiring diagrams showing which components are EN16, pin 84 (P) and EN37, pin 4 (P)?

Below are some pictures of what I'm seeing.
#1 is Bank 1 Oxygen Sensor connectors by the firewall. The right, light grey connector is Upstream Sensor 1 and the left, dark grey / black connector is Downstream Sensor 2.

#2 & #3 are Upstream Sensor 1

#4 & #5 are Downstream Sensor 2

Thanks in advance to anyone willing to help me figure out how to test which one of these oxygen sensors is bad and replace it without paying $500 labor at the Jag dealer.

 

If you download JTIS
https://www.jaguarforums.com/forum/x...archive-66034/
you'll find everything you need in there.
The DTC you have is for Upstream sensor 1. At nearly 100K miles I think you need to replace it but this isn't an engine I know a lot about.

 

Just fixed my 2.1 Petrol X type Engine Malfunction Warning indication.

Code Reader indicated O2 sensor, Bank 1, Sensor 1. Cleared code,replaced Bank 1 Sensor 1 but light came straight back on. Checked with code reader again, P1646 returned, not P1647 (read on).

Searched internet and found out that the 2 black wires of the four wires on the O2 sensor are the heater coil. Measured all black wires on all 4 connectors on the car by disconnecting O2 sensor plug,putting some thin wire into the sensor socket and measuring resistance with the following result:
Bank 1 Sensor 1 = 1ohm (New one)
Bank 1 Sensor 2 = 6ohm
Bank 2 Sensor 1 =2100ohm
Bank 2 Sensor 2 =14ohm

The reading from Bank 2 Sensor 1 being a lot higher than the others shows something is wrong.

Replaced Bank 2 Sensor 1, after starting/stopping the engine a few times the Engine Malfunction Warning light went off, hooray!!