Hey there, I recently had my check engine light turn on on my 2004 Jaguar XKR (4.2). It’s throwing codes P0305 (Cylinder 5 Misfire), P0307 (Cylinder 7 Misfire), P1316 (Injector Circuit/IDM Codes), and P0783 (3-4 Shift). I had all the spark plugs, coil packs, transmission oil, transmission filter, and oxygen sensors replaced within the past few months. I’ve used the correct Denso packs & NGK plugs. What else could it be? It seems I can’t get rid of the misfires no matter what I try. Any advice is welcomed.

 

No doubt you’re expecting this reply,
“what condition is you battery in”
thought I’d get in first. As you know it’s a major cause of fault codes

 

Is the answer in the question? Do I read 11.22V at the bottom of the picture?

 

yes you do.

that's way too low. It should be 12.6 v minimum even after sitting for a week.

The issue may not have anything to do with the battery or charging system. But the low voltage needs to be resolved first and foremost, imho.


Z

 

What battery do you recommend I replace it with?

 

I put a NAPA AGM Gold battery in my 2002 XKR about 7 years ago when I bought the car. Still working OK.

i keep the car on a NOCO Genius 10 battery tender when not being driven.

I believe that does help extend the battery life and keeps the XKR electrical gremlins at bay.

Z

 

I just replaced it with the DieHard Platinum AGM battery that was recommended in a previous thread. The car is daily driven, I’m at about 150,000 miles. Let’s see if this fixes the issue! If it doesn’t, where should I try next? I know I can swap the spark plugs to see if the misfire switches locations or swap the coil packs to check the same thing. Should that be the first test? Thank you!

 

The best part lace to get a battery from is Tayma batteries online, delivery next day and cheaper than anywhere else even after delivery charges. I have a yuasa, if you compare the specs between different batteries they seem the best, I use them on all my vehicles.

 

Check the battery voltage first
Then check the sprak plugs if there's oil around it sometimes the spark plug oil seal leak and cause misfiring
Did you use new ignition coil ? Or used one?
​​​​​​

 

All ignition coils and spark plugs are brand new, I’ll definitely have to check the oil seal next. Thank you!

 

The P1316 meaning looks very wrong - anyone confirm?

 

^^

From Jaguar 2003 DTC list, but 2004 is the same: