Just had to take my 96 xj6 in for inspection (DEQ) and new tags. It passed all the smog checks, smoke test, and visual inspection, but failed over all because it had these diagnostic codes come up.

P0400 Exhaust gas re-circulation Flow Malfunction

P1775 Manufacturer Specific Code

P0411 Secondary Air Injection System Incorrect Flow Detected

P0753 Shift Solenoid A Electrical

P0430 Catalyst System Efficiency Below Threshold (Bank 2)

P0420 Catalyst System Efficiency Below Threshold (Bank 1)


So my question for anyone here that would like to answer is where should I start on this?

My first inclination, now that I have time to do it, is start googling each of these codes and check for mechanics videos of how they fix each thing. Which I will begin after posting this

But I would love the opinion and experience of anyone here on the forums that has dealt with and taken care of any of these problems

Cheers and thanks!

 

I've moved your question from XJ ( X305 ) XJ12 to X300 forum for you.

Does OR require a P1111 (all Onboard Tests completed) to show which prevents you just clearing the codes?

Graham

 

Here's the extact from the Jaguar DTC Listing for the codes you have recorded. The Possible Causes for each are shown in the right hand column:



Not the neatest extract I've ever put together but it should give you the information to start troubleshooting the causes.

Graham

 

I wonder how long those codes have been there.

Is the car running well? Is the Check Engine Light on?




Removing the EGR valve and cleaning away the caked-on deposits often helps


The diagnostic chart already provided gives the most likely causes. However, some X300 owners have never been able to identify a fault that would explain why these two codes pop up. There's some speculation that the fault is an anomaly within the OBD system itself.



My first thought is to clear the codes, drive a few days, and see which one come back, if any. The question posed by GGG regarding 'onboard tests completed' is important, though.

Cheers
DD

 

Doug is spot on, as usual!

 

Do you have a CEL light on?

About once a week or so when I start driving the car for the first time that day it will run rough while at a stoplight. I doesn't run rough going down the road. I get code P0400 and P0430. As quickly as the roughness at stoplights started it stops. I just clear the codes so I know if they are old or new.

The car runs will. I just topped it off today and on 580 miles I averaged 19.4 (calculated) MPG running what I would call standard urban driving. Some freeway at 65-75, some stoplight to stoplight.