Cannot clear code po1647

DANOC22

MEMBER
2004 JAGUAR X-TYPE
3.0L
6 CYL
2WD
AUTOMATIC
130,000 MILES

I replaced both sensor, cleaned the catalytic converter. Heat tested the catalytic converter at 203 on top 370 on bottom. Used carburetor cleaner to check for vacuum leaks. I unhooked the battery to reset drove 200 miles. This is a California car 11/03 date of birth. Light comes on immediately when cold and when warm not long after I turn it off. I am lost.

1 Reply

STEVE W.

MECHANIC
13,465 POSTS

P1647 is a sensor circuit code for the upstream sensor on bank 2 That is the top sensor on the front of the engine. It could be a bad sensor, however as you replaced it that probably wasn't the problem, more commonly a fault in the wiring to the sensor, either open or shorted is the problem. The fastest way to tell would be to look at the live data coming from the sensor to the PCM. However without a scan tool to read the data the next method involves going to the ECM and testing there as well as testing at the sensor end itself. You test for shorts between the wires and each other or the wires and ground. Or for an open wire in the harness. This is the OEM method for doing this, and why the scan tool is much simpler. With a scan tool you can look at the voltage from the sensor and see if it is zero or some odd voltage. Before doing these tests I suggest looking at the connector on the sensor and then following the wiring harness along looking for any type of damage or corrosion to the wiring. Check any connectors you find as well.

K : P1647. LEFT-HAND BANK HO2S

CHECK THE CONSTANT CIRCUIT OF THE LEFT-HAND BANK H02S FOR OPEN CIRCUIT
1. Disconnect the H02S electrical connector EN32.
2. Disconnect the ECM electrical connector EN16.
3. Measure the resistance between EN16, pin 108 (P) and EN32, pin 4 (P)
- Is the resistance less than 5 ohms?
Yes = Good
No = REPAIR the fault in the circuit. CLEAR the DTCs. Test for normal operation

CHECK THE CONSTANT CIRCUIT OF THE LEFT-HAND BANK H02S FOR SHORT TO GROUND
1. Measure the resistance between EN16, pin 108 (P) and GROUND.
- Is the resistance less than 10,000 ohms?
Yes = REPAIR the short circuit. CLEAR the DTCs. Test for normal operation
No = Good

CHECK THE CONSTANT CIRCUIT OF THE LEFT-HAND BANK H02S FOR SHORT TO BATTERY
1. Connect the ECM electrical connector EN16.
2. Turn the ignition switch to the ON position.
3. Measure the voltage between EN32, pin 4 (P) and GROUND.
- Is the voltage greater than 5 volts?
Yes = REPAIR the short circuit. CLEAR the DTCs. Test for normal operation
No = Good

CHECK THE VARIABLE CIRCUIT OF THE LEFT-HAND BANK H02S FOR OPEN CIRCUIT
1. Disconnect the H02S electrical connector EN32.
2. Disconnect the ECM electrical connector EN16.
3. Measure the resistance between EN16, pin 107 (Y) and EN32, pin 3 (Y)
- Is the resistance less than 5 ohms?
Yes = Good
No = REPAIR the open circuit. CLEAR the DTCs. Test for normal operation

CHECK THE VARIABLE CIRCUIT OF THE LEFT-HAND BANK H02S FOR SHORT TO GROUND
1. Measure the resistance between EN16, pin 107 (Y) and GROUND.
- Is the resistance less than 10,000 ohms?
Yes = REPAIR the short circuit. CLEAR the DTCs. Test for normal operation
No = Good

CHECK THE VARIABLE CIRCUIT OF THE LEFT-HAND BANK H02S FOR SHORT TO BATTERY
1. Connect the ECM electrical connector EN16.
2. Turn the ignition switch to the ON position.
3. Measure the voltage between EN32 pin 3 (Y) and GROUND.
- Is the voltage greater than 5 volts?
Yes = REPAIR the short circuit. CLEAR the DTCs. Test for normal operation
No = INSTALL a new left-hand H02S. CLEAR the DTCs. Test for normal operation.

If the DTC is repeated, install a new ECM. Before replacing an ECM, contact dealer technical support.