About 4k miles ago we replaced all 4 O2 sensors on my 2004 D2. We had a p0420 code and we replaced the cat which fixed that. Now I have an intermittent p1173 code. We've checked the O2 sensor and it is working fine. Does anyone have any ideas on what could be triggering the p1173 code even with the O2 sensor working?

Thanks for your help!

 

I've read some threads about the p1173 code but all seem to point to a bad O2 sensor which appears to be fine in my situation. One thread mentioned a breather issue but I'm puzzled as to why that would trigger a p1173 code.

 

Still having the occasional p1173 code. I changed out the front O2 sensor and it is working fine.

 

My p1173 code comes and goes. Any ideas what could be causing that? I guess that I could change to a different brand/model O2 sensor. I am using the "economy" Walker unit with the round tip and slots. Different than the OE Walker that is square and has dimples.

 

The emissions crap in these things is so finicky it wouldn’t surprise me if that was the cause. I’ve put 2 new MAFs in, and when I went back to the OEM one, no more codes. It really sucks.

 

Have you guys reset adaptive values when replacing this stuff? Over time the ECU will adjust how it interprets the readings from these devices and it needs to be told there is a brand new part. Just a thought.

 

Doing an ECU re-set is not a bad idea. I think that I'll replace the upstream O2 sensor with the Walker OE unit and then disconnect the battery to clear out the ECU adaptive values.

Next step is to replace the MAF sensor. Rather than replacing the entire MAF sensor/housing, has anyone had any luck with just replacing the sensor with either a Delphi or BSE branded sensor? Otherwise, I'd have to buy an entire Bosch MAF unit which is more expensive, but its a Land Rover..I know...

 

I'm currently using a Delphi replacement. I have noticed no difference between the Bosch I pulled. I was chasing a P0171/P0174 code. It has been working fine for about 4k miles. Have not noticed any difference between the Bosch and Delphi. I ended up replacing the fuel injector seals to clear up my issue.

 

Thanks for the feedback. How did you know to replace the injector O rings/seals? Do you need to remove the intake to do that?

 

@NVDiscovery A little late on the reply. I never saw the alert but to answer your question yrs later . I was chasing down the P0171/P0174 and tried several things vacuum related. Smoke test and replacing old vacuum lines. It kept coming back. The idle would jump up above 1K after driving on the highway. Gas mileage was worse than normal. Reading several threads on those codes people pointed to the fuel injector seals as a possible culprit. I replaced head gaskets several years before and thought maybe I pinched one and it was now failing. In any event, I pulled the intake and took them out. Several seals were hard and brittle. I sent the injectors out for service. Installed the new o-rings on them and problem fixed. One of the more frustrating things I have had to track down on this Rover.