Have been trying to figure this code out and no luck. Vehicle runs fine only engine light on. I have changed the throttle body and replaced/repaired the air assist hose that goes to the intake. I have checked the voltage and ground readings on the valve, all were good (wiggle tested wires too). I have smoke tested the engine and no vacuum leaks. I do have a code reader and clear the code, but it comes back after a while. It usually comes back after warmup and after second or third start of the day. Now I was going to clean some extra injectors (16) I have and switch out the ones I have on the car. But I noticed one thing different from these sets. One older set has the white Pintle Caps these have four tiny holes in them for the air assist air to enter the fuel stream (on the injectors). the second set (black pintle caps) look newer or refurbished, and these have Pintle Caps that have four indents that look like holes for the air assist, but they are not holes. In other words, there is no way for the air assist system air to get to the injector fuel stream. Now could this be a problem with this Code P0065? I haven't taken the injectors out of the car to look at them because I was just going to replace them with one of the sets after I serviced them. Oh, the current Injectors in the car are refurbished ones from Ebay (lifetime warranty ones) but company is no longer selling on Ebay, go figure... Any Ideas? I just have this thing about engine lights on!!!
2001 xk8 convertible

 

used oe injectors

 

I had been chasing a code and had replaced the factory injectors with refurbished ones. Now Chasing this P0065 code...Wondering if the upstream o2sensors wound give me code. Had a rat chew the wires on the sensor... wires seemed fine no o2 sensor codes. Just don't know where to go...Have another throttle body that I'm going to throw at it. If it doesn't work, then at least I have two spares. LOL

 

the strategy to monitor AAI performance 100% uses the upstream A/F sensor but i can guarantee you they haven't failed.

 

OK, just grasping for straws.... Heck I even considered swapping out engines!!! LOL
Really don't like the engine light on!

 

Well I decided to check the injectors and found that some of the tiny holes in the injector pintle caps were clogged. Sooooo decided to rebuild or refurbish injectors . Added new pintle caps and changed all seals. So far the Code has not come back on.