Absolutely, and to the Op, jfall is one of the truly knowledgeable members who has helped me out with similar problems. In fact, a leaking head gasket is what caused my cats to fail. So it is wise advice to sort that out before putting new ones on or you may end up replacing them again and again.

Best,

Charlie V

 

Finally got the truck back from the mechanic.

First let me point out that next time Occam's Razor will be followed faster, but I will be doing it myself, and less trust in others to take the time.

RoverMasterTech and Shade Tree were correct. The 2 and 8 wires were installed incorrectly, switched, at the coils. This miss fire was dumping gas into the catalyst causing a false code. This wasn’t the original problem but what happened after having the coils replaced.

Not mad at the first mechanic as he made an honest mistake and didn’t think to re-check. I am very irritated and the second and third as I specifically asked to check the wires and they said all was good.

NEW TIP to switching wires at the ignition coils without pulling off the manifold:
* Disconnect windshield washer hose and remove hood (4 bolts), make sure to mark the bold placement on the hood and brackets so it lines back up correctly for re-installation.
* Pull the top wire harness away from coils and zippy tie to manifold.
* Lay carpet on top of engine so you can lay down.
* And if you are like me, with Lincoln logs for fingers, have your wife, significant other, or closest lady friend with small hands, crawl up and disconnect and switch the wires.

So far so good, no new codes except for my Tre’s Amigos.

 

good to hear its fixed and thanks for the tip- ill be replacing my wires here soon enough.

 

Sometimes it is the simplest things... but you said that. Congratulations on the easy fix.

 

Hello all, new to this site, sorry for long read but I need help. I have a 2010 range rover sport hse with about 156000kms. This morning, I was on a really bumpy ramp onto the highway. When it came time to switch lanes, I got the "restricted performance" code along with a serious drop in power. I could barely maintain highway speed. Car seems to run fine while at high speed, just not a lot of power. When I exited the highway, the engine was running rough at lower speed and while waiting at a red light the whole car was shaking and idling rough. Tried turning it off and back on, no change. Upon pulling into a parking spot at low speed, the car shut off on me. Put into park and restarted, was able to park but engine still running rough and feels like it wants to choke out. I hooked my scanner up and it is saying misfire in all cylinders, misfire detected on start-up and pressure line solenoid line 5 fault short circuit. Yesterday I filled up with mid fuel instead of premium, but that's the only change I've made. Tried unplugging battery and reconnecting and also added some octane booster to try and counter the mid fuel grade. Unplugged air flow sensors and plugged back in. Still no improvement. I'm wondering if anyone has had the same problem and knows the fix? Thanks.