Moving this to the proper forum.

 

Has there been any reply to this issue?
I keep on having the amber engine warning light coming up on my 2001 XK8 with the error code P0066:

P0066 Air Assisted Injector Control Circuit or Circuit Low

I havn't found much about this specific one on the forum so did a lot of cleaning: hoses, MAF sensor, throttle body, electric connectors.
The car runs fine and after resetting the OBD and running for sometime after a while (sometimes 2-3 hours later) the amber engine warning light goes back on but with no effect on the car's behaviour.

Can it be the connectors or the wiring? What could happen if I continue to drive with the amber engine warning light on?

Thanks for any advice

 

The documentation here has more detail on P0066:

AJ27_2001_OBD2.pdf

On the face of it, it looks like it is part of the throttle body. As per the documentation, it takes a couple of trips to trigger the light, so even if the light is off after you reset it, it probably has not worked since the light first appeared.

You might have to have the throttle body rebuilt for this to clear up. The other option is to locate a carefully chosen used part, and swap out the valve. As posts about this are quite rare, this valve might possibly be normally reliable, which makes a used unit an option. A third option would be to contact a reputable re-builder and see if they would ship you a "known-good" valve, assuming you can install this yourself.

Bonne chance, keep us posted.

 

The purpose of the valve is described by JTIS as:

Air assisted fuel injection control valve with integral air feed.

The air assist injection improves the atomisation of the fuel spray pattern during cold temperatures. This reduces the hydrocarbon (HC) produced by combustion. By improving combustion stability when cold, allows the use of increased ignition retardation for faster catalyst warm up, providing a further reduction of HC emissions.

You can identify the valve connector on the throttle body assembly as it's the only component with three wires - Black/Pink, Ground; Red/Blue, ECU, 0.98 V @ 10 °C (DECREASING VOLTAGE WITH TEMPERATURE INCREASE); and White/Blue, Switched Live 12v.

Problems with damaged/corroded/dirty connectors at the throttle body are well known and you might like to eliminate them first.

 

I've learned over the years that if you remove a connector you apply dielectric grease to it then plug it back in. The grease is a moisture barrier.

 

Thank you all for your kind suggestions: I will start with the connector and I am already prepared to have the valve and / or throttle body oberhauled:

I shall do that in the upcoming winter period and I will keep you informed of course.

Merci...

 

Hi SputNic, did you solve the P0066 problem?
I have exactly the same error code after a while that I started the engine....

 

Hi,

In fact not yet. I did check the connectors and the air intake as proposed by other members but no change. Since I am driving now over 1 year with this fault and the car is still running smoothly I guess it is not super urgent (I am only doing 3000km/year) but maybe I was only lucky so far.
This winter though I really should be giving the throttle body to a specialist.

Is your car still running or does it go into limp mode? If not it seems not to be very urgent.

 

If it were me I would check the plugs and spray them with contact cleaner first.



Link http://www.jagrepair.com/images/TSB/XJ/303-S498am-1.pdf

 

Hi SputNic, thank you for your answer,
I have a xk8 4.0L 2002 with 53000 km, the throttle body is the one with the AACV.
She starts idles and runs fine, without any additional problem or limp mode. Clearly it is a minor problem as it does not affect any perfomance or safety but the engine light on is quite annoying....
I have a diagnosis tester and I can switch the engine light off.
When I start the engine from cold and let it idles, without touching the gas pedal, after the water temperature has started to rise to the second mark, the engine light comes on with code P0066.
When I start the engine from cold and warm up let' say at fast idle, (pushing slightly on the gas pedal) and warm the water above the second mark the light do NOT came on.
When I start the engine from cold and I drive, if the engine is cold and I release the gas pedal, the light came on.
When I start the engine from warm, light do not came on.
So the "critical" situations are starting from cold, and deceleration.
The air hose that arrives to the AACV has no leak, I sprayed the connectors with electrical contact cleaner....
next step will be to buy a second hand throttle body as donor of the AACV actuator and substitute it into my throttle body.
I must confess that I am little scared of
substituting the AACV actuator and I dont know if it is possible to do that with the throttle body mounted on the car.
I will receive a 2nd hand throttle body next week and I will start to figure out how to remove the AACV actuator from this one.....
any suggestion is super-accepted !!!.........

 

Hi Gus, hi SputNic, thank you for your answer,
I have a xk8 4.0L 2002 with 53000 km, the throttle body is the one with the AACV.
She starts idles and runs fine, without any additional problem or limp mode. Clearly it is a minor problem as it does not affect any perfomance or safety but the engine light on is quite annoying....
I have a diagnosis tester and I can switch the engine light off.
When I start the engine from cold and let it idles, without touching the gas pedal, after the water temperature has started to rise to the second mark, the engine light comes on with code P0066.
When I start the engine from cold and warm up let' say at fast idle, (pushing slightly on the gas pedal) and warm the water above the second mark the light do NOT came on.
When I start the engine from cold and I drive, if the engine is cold and I release the gas pedal, the light came on.
When I start the engine from warm, light do not came on.
So the "critical" situations are starting from cold, and deceleration.
The air hose that arrives to the AACV has no leak, I sprayed the connectors with electrical contact cleaner....
next step will be to buy a second hand throttle body as donor of the AACV actuator and substitute it into my throttle body.
I must confess that I am little scared of
substituting the AACV actuator and I dont know if it is possible to do that with the throttle body mounted on the car.
I will receive a 2nd hand throttle body next week and I will start to figure out how to remove the AACV actuator from this one.....
Maybe have I to check the relay and the fuse in the ECM compartment?
any suggestion is super-accepted !!!.........

 

The code book details:



Start by checking the plug. Is there a good ground? It looks like pulse width modulation control. Is there some voltage at the plug for this? This would indicate that whatever the ECU sends to control the valve makes it over the harness.

Also, Check the valve itself for "infinite" or zero resistance. See if you can apply voltage to the valve directly. Does it show any sign of life (noise, vibration)? Last, check if the valve shows any sign of air control. Is it sealed when disconnected?

Best of luck, keep us posted.

From Nivelles, BE?

 

Hi Gus
I have a 2002 XK8 with 52,000 miles and have just had the same code error. Did you have any luck replacing the AACV actuator?
Tony