How to change a Knock Sensor on a Jaguar AJ27 Engine

One of the common problems of the Jaguar V8 engines is knock sensor failure.
A faulty knock sensor will set the ignition timing in full retard and you'll get only a weak performance.
The failure is accompanied by the amber warning light and a DTC Message "Restricted Performance".
A knock sensor failure has not to be a permanent problem. Intermittent failure is common, but still the sensor has to be changed to get rid of the problem.

To verify if the problem is indeed a knock sensor failure and to check whether it is Bank 1 (right side of the car) or Bank 2 (left side of the car) you'll have to get the OBD codes read out.

The codes are as follows:

P0325 Knock Sensor 1 Circuit Malfunction (Bank 1 or Single Sensor)
P0326 Knock Sensor 1 Circuit Range/Performance (Bank 1 or Single Sensor)
P0327 Knock Sensor 1 Circuit Low Input (Bank 1 or Single Sensor)
P0328 Knock Sensor 1 Circuit High Input (Bank 1 or Single Sensor)
P0329 Knock Sensor 1 Circuit Intermittent (Bank 1 or Single Sensor)

P0330 Knock Sensor 2 Circuit Malfunction (Bank 2)
P0331 Knock Sensor 2 Circuit Range/Performance (Bank 2)
P0332 Knock Sensor 2 Circuit Low Input (Bank 2)
P0333 Knock Sensor 2 Circuit High Input (Bank 2)
P0334 Knock Sensor 2 Circuit Intermittent (Bank 2)

There are two knock sensors located on top of the Engine, approximately in the middle of the 4 cylinders at each bank.
To get access to the sensors the black plastic engine cover with the "Jaguar V8" imprinted on has to be removed.

There are two types of knock sensors.
The "old" ones that are of a "screw-in barrel type" and the newer ones that are just bolted on.

I describe the replacement of the bolt-on type knock sensor on Bank 2 in the following documentation on a 1999 XJ8 AJ27 engine.

Be careful!
Knock sensors are piezo electric devices that are very sensitive! If dropped, over-torqued or struck they will probably be destroyed.
As knock sensors are sensitive to a sudden temperature change they are also easily fractured by steam blasting a hot engine.
So handle the knock sensors with great care and let the engine always cool before fitting a new sensor!



Here's my How-To-Write-up...


That's where we start...




Remove the black plastic engine cover.
(It is just clipped on so just unclip the two black plastic hoses on top of the cover, bent them slightly away, and pull the cover off.)




In here's the left-hand-side knock sensor hidden...




Unplug the electrical connector of the knock sensor located at the side of the black plastic thermostat housing.






Remove the connector from the retainer clip.
(To not break the connector use a small bent tool to push the latch of the connector back and slide the connector downwards and off it's retainer clip.)

Here's my "tool" and a close-up of the connector:






"Special tool" in use...






Loosen the 13mm screw nut that holds the knock sensor.




Fill a 13mm wrench socket with grease to hold the nut in the wrench socket.




Remove the screw nut and carefully lift the wrench with the nut "glued" into it up.




...

 

...
Get yourself two pieces of wire and bent one side into a small U-hook.




Use one U-Hook to pull up the knock sensor and with the second wire carefully guide the attached cable and it's connector out.








Here's the defective knock sensor vs a new one.



(I ordered the new ones with www.autopartswarehouse.com, Item No W0133-1655837, $27.95 free shipping to the US.
They are for a XKR but fit theXJ8 as well. Only difference is that the cable is a few inches longer than the one of the original sensor, but there is enough room to tuck it away nicely.)

Use some WD40 and a paint brush to clean the surface on which the knock sensor was/will be mounted.








Insert the connector and the wire, guide it with the U-Hook-wire towards the front and lower the knock sensor onto the bolt.



To insert the new knock sensor use the shaft of a wooden spoon (or something similar) to hold and guide the knock sensor into position.






Hold the knock sensor in place with a large screwdriver and carefully remove the wooden shaft.




Slide the connector onto the retainer clip and connect it to the harness.




Grab the wrench socket with the 13mm nut still "glued" in and carefully guide the nut onto the bolt.




Tighten the nut to hand-tight. (Torque = 20Nm or 14 lb/ft, thanks to "xjrguy" for the torque data!).

Replace the engine cover and you are done!

It took me about 15 Minutes per side but I have been there before.
(As my first DTC appeared I interchanged the knock sensors just to be sure that the knock sensor was the culprit and not some bad wiring/contact.)


Good Luck!


David

P.S.
To follow that write up is completely on your own risk!
If some damage occurs following that write-up I'm in no way responsible!

 

Nice write up. Thanks!

 

Thanks for your time and pics , this will be FAQ

 

2 things to add
1) many times that little plastic rib on the intake runner keeps you from taking the knock snesor up as it interferres. Break or cut it off with side cutters.
2)i just use a telescoping small magnet for the nut and knock sensor to feed in/out. Anyone that works on a car should have 1 for droppped tools, bolts/nuts and install removeable of many metal parts. Works real well on stuff under the car that always seems to roll under the car furthest fromt your reach.

 

Sweet DIY man. I need to do this soon and this helps a lot. Thanks!

 

THANKS for taking the time to do this DIY post! I ordered two knock sensors and if the lenght of the pigtail is the only difference...I saved myself a lot of $$$$$. Thanks a lot!

 

The AJ85676 is designed for the 4.2 engine ( BTW $27 is the full jaguar list price).
4 liter engine, being XJ or XK, use the LNE1692AA which is way more expensive at $100 list.

I'm not sure if that matter but I would worry a bit about using sensor designed for an other type of engine.

 

I'll give it a try since it has been done before. If it is not the right set-up it will probably show some DTC's and I'll take them out. Thanks for looking out!

 

You won't regret that decision.

 

Wow...Only a month old....Well, let me be late to the party as usual. I went to do this job today on a clients 1998 Vanden Plas with the 4.0. Sadly, it requires a 15/16 socket to remove the knock sensors. Why "sadly"? Because a 15/16 wont FIT in between the intake runners. I'm pretty sure this will require a removal of the intake? Anyone else know?

 

I'm pretty sure I used a long skinny metric socket (12 or 13 mm) with a flex extension. The left side went easy but on the right side (passenger side) you might need to brake the plastic edge (runner) that is in your way. It won't hurt anything doing it. Have fun!

P.S. The knock sensors listed by David work just fine on my 2001 VDP and they were a lot cheaper.

 

No, when I say 15/16 socket, I don't mean metric. I mean SAE. Mine is DIFFERENT from the one pictured in this write up for some odd reason. It's ok though...I just clipped the wires, re-wired the connector plug, and checked connections. Then I went and had the codes cleared, and now it is fine.

 

So you probably have the older barrel-type knock sensors.
I have no experience how to remove these...

 

Hi Folks,
First, thanks, fantastic writeup. I have an intermittent knock sensor problem since a coolant leak (heater pipes in the 'v').
How confident are people that the cheaper AJ85676 will substitute for the stock LNE1692AA (1999 AJ27 3.2)?
I know it will cure the fault codes, but my worry is that it might be less sensitive to knocking (and allow engine damage over time) or more sensitive and restrict performance.
If you have retrofitted AJ85676, have you noticed any extra pre-ignition?
Are the two parts manufactured by the same company?
My dealer recommended the OEM LNE1962AA and would not be drawn on the suitability of AJ85676.
Thanks, Aidan

 

Both knock sensors are made by DENSO to Jaguar specifications.
I changed both knock sensors with the "cheaper" ones I mentioned above, use them now since half a Year without any problems.

If you are still concerned - go and buy the original (more expensive) part and if it is just for your peace of mind.

David

 

Thanks David,

Your experience is good enough for me. I have ordered one AJ85676 and hope to fit it at the weekend.

Cheers, Aidan

Update:

Fitted cheaper AJ85676 in June. No fault codes or knocking since.

Thanks Again, Aidan

 

the "spec'd" torque gives the required sensitivity, more/less torque = more/less sensitivity

 

I've been running with the ones suggested by Dave for almost three months now...so far, NO PROBLEMS!

 

Excellent!! I need to do bank 2 on my vdp.
This will help!!
thx