WJ P0161

[OverlandZJ]

Just pulled the WJ onto ramps to replace a faulting CPS (P0320) and noticed it threw a second code as i was doing so.

P0161 (M) 2/2 O2 Sensor Heater Failure

What does the above mean?

 

[wheeling365]

Sounds like the computer thinks one of the O2 sensors has a bad heater element. Newer O2 sensors are 3 or 4 wire units that have a heater element in them. The purpose is to get the sensor hot faster so the ECM can use the info from it faster.

The 2/2 sounds like it would be a downstream sensor. Possibly the one behind the converter.


http://www.obd-codes.com/p0161

 

[OverlandZJ]

Thanks.. after replacing the CPS and clearing the codes it has not reappeared.

But during a short drive later it threw P0352.

P0352 (M) Ignition Coil # 2 Primary Circuit Peak primary circuit current not achieved with maximum dwell time.

Last summer i had these codes (0351-0352-0353) after swapping in a low mileage rebuild that had the oil pump drive and cam sensor installed. It would throw each code sequentially and stall whenever i would depress the accelerator. Research showed somewhat common for the cam sensor being out of range.

Not having a DRB scanner i loosened the drive bolt and slightly rotated the assembly clockwise just a tad. This cleared the codes and stalling issue was gone when accelerator depressed. It did seem to run just a tad rich and i knew it needed a proper adjustment with a DRB scan.

I'm baffled why this would reappear after a CPS swap?

I'm also wondering if the CPS airgap could be suspect. I followed the directions of applying slight pressure while installing and tightening the retaining bolt. I also left the felt pad on.

 

[wheeling365]

I recall reading about someone modifying the CPS mounts to advance the timing. I guess it could be possible that the replacement sensor has the mounting tab shifted just a tiny bit left or right in relation to the opening changing the timing.

I'm not sure that it would really cause the symptoms your having though.


The code makes me think that the middle coil of the coil rail isn't charging to the desired voltage that the ECM expects and in turn would cause a weaker spark in cyl 3 and 4. If it was bad enough I would expect to see a misfire code for one or both cylinders expecially under load.

I haven't done much troubleshooting on the coil rail systems but I'd try looking at the connectors and grounds first as thats cheap and easy.

 

[Talyn]

You don't need a DRB to set the cam sensor. http://www.google.com/url?sa=t&rct=...sg=AFQjCNGbe6ovT_jXzPa5RV2tMl7KnOtGPw&cad=rja

I had that P0352 on my XJ when the CPS went bad, but it was for all 3 coils.

 

[OverlandZJ]

I cleared the code and went for a nice bit of ride, stop and go mixed with some open road up to 55mph. Ran beautiful, no codes.

Talyn, that link wont work for me. But i believe it to be the "toothpick" method as mentioned in the FSM. Thats my next move if it reappears. However in the FSM it recommends the DRB to make sure it sync's the injector pulse/timing?

Thanks.

 

[Talyn]

Yes, that is correct with the tooth pick. Find TDC on #1, put toothpick in drive, drop in block. The DRB isn't 100% necessary. It only gets it perfect, which isn't needed to run correctly. I've reset mine many times and never had any issues.

 

[OverlandZJ]

OK, i thought it was absolutely necessary by reading the big bold text in FSM. Thanks for setting me straight Talyn.. much appreciated.

 

[OverlandZJ]

Took it for another ride, ran good and no P0352.

But it did throw the original P0161 oxygen sensor code. Crawled under and found the issue, the harness had just enough slack in it to contact the front driveshaft. I must not have clipped the harness well enough when i installed the engine. I'll pick up a new sensor.

I found listings for upstream and downstream sensors for both Federal and Cali emissions, my WJ has Cali and the four sensors. Are both the downstream sensors the same part#?

 

[OverlandZJ]

I found listings for upstream and downstream sensors for both Federal and Cali emissions, my WJ has Cali and the four sensors. Are both the downstream sensors the same part#?

Found my answer, both downstream sensors are the same part#.. and differ from Federal emissions setup.

Found a great deal on new MOPAR sensors on ebay..

 

[OverlandZJ]

New sensor in, running well with no codes.. :fingerscrossed:

I saved $63 off the typical $100 for a Mopar sensor #56041212AF on ebay, guy had seven of them NOS. Worth the few days wait.