I am got these two codes the last two days. Currently the car seems to be driving great other than these and the fact it set restricted perfromance one of the times it set the CEL.

For about the last month there has been a misfire when the car is warm, only when warm with no CEL or codes set. I replaced all the spark plugs (about 20k miles on them) and swapped out the coils one by one every time I went driving with a known good coil hoping it was a bad coil. After going through 6 of them the misfire went away and since Christmas day the car has been driving great. I assumed it was that bad coil

Yesterday it set the CEL and I pulled these two codes P172 and P175 which are each related to rich condition on both banks.

As it is on both banks, this makes it unlikely it is an O2 sensor or a single bad injector, coil or plug. I am at a loss for what it is.

Could this be related to the misfire that went away and got better?

 

Check the LTFT and STFT while driving?
I had this on one of my 2000MY XKR and replaced the MAFS
The readings were 'more correct' with the replacement MAFS.
Be sure to remove power to the ECM to reset the FUEL TRIMS each time a component is replaced.
They need to start from RESET and not continuing from the last setting.
It will take longer to get an true reading.

 

The Denso branded MAF sensor for the 4.0 XKR’s is jaw dropping expensive.

As far as I’ve been able to discover, only the Jaguar XJR shares it with the XKR, so rarity has kept the price high. The XK8 on the other hand uses a more common MAF and its Denso price is reasonable.

You’ll find many 4.0 MAF’s on Amazon that aren’t Denso manufactured and I’ve never had luck with any of them .


you might try cleaning it (repeatedly) with CRC MAF sensor cleaner. The wires deep inside it are the ones that need attention, take care not to touch them with anything but the spray.

when I had the same codes, it took 3 re-peats with the CRC spray to get the issue to go away. Best of luck with it, the 4.0 XKR’s are getting a little finicky in the fuel trim department.

Z

 

+1 on Bob's and Z's observations.

Here are the definitions and published possible causes of your codes from the DTC Summaries manual:





One common issue I've observed is that when the Engine Coolant Temperature Sensor fails and continues to send a "Cold" signal to the ECM, the ECM will continue to apply cold-start fuel enrichment even after the engine has reached full operating temperature. The same can happen when the thermostat sticks open. So while you are monitoring Live Data to observe the STFTs and LTFTs, also observe the coolant temperature signal to see if it is implausibly cool or cold or if it takes too long to warm up.

Cheers,

Don