I've got a 2003 XJ8 with a 4.0L engine that I just had replaced. Since then I've been getting intermittent Failsafe Engine Mode warnings with a concurrent loss of cruise control. I took it back to the mechanic and was told the computer was generating fault code P0175. This translates to potential problems with the Engine Coolant Temp sensor, Mass Air Flow sensor, Intake Air Temperature sensor, or Throttle Position sensor among other potential causes. My mechanic says Jaguar doesn't publish the "bench test" specs for these sensors for further troubleshooting. Anyone know how to get the tech data so that the sensors can be verified operational?

 

Yes you need to check live data particularly fuel trims,
The code shows as Bank 2 System too rich which has many possible causes look at this link:

Jaguar P0175 OBD/DLC Error Code - System Too Rich

I would check fuel trims first and then work from there.

 

You're better posting this in the X308 forum, the one for your car so you can get inputs from fellow owners who may not look at this forum.

 

Thanks for both the responses. I'm obviously a novice at this type of site and didn't know the proper protocol. I've since read the new member info and am doing additional research on how to phrase my questions more completely. I'm concerned that I may not be adequately equipped with all the tools necessary to personally resolve my car problems, despite all the helpful advice that I may receive on this site.

 

Stick at it, people will usually try to help.

 

Thanks again. I've posted a new member intro and updated my signature with the suggested data.

 

Hi Bob,

I have moved your thread to the forum for the X308, which is the Jaguar factory project code for your 2003 XJ8 4.0L.

At the link below you can download the Diagnostic Trouble Code (DTC) Summaries Manual, which lists possible causes of your P0175 code, which indicates combustion is too rich in Bank B (Bank 2):

http://www.jagrepair.com/images/Auto..._2001_OBD2.pdf

Note that before all the potential sensor circuit issues, it lists such things as a blocked air filter, blockage in the fuel system return lines, leaking fuel injectors, and fuel pressure regulator failure. Note also that it doesn't say one of your sensors is definitely bad, but that the ECM is receiving an incorrect signal from one of the sensors. This is often due to looseness or corrosion in an electrical connector or at a ground stud, or a problem with the sensor's wiring harness such as chafed insulation allowing a short to ground.

You can download the Engine Management System Service Training Manual at the link below, which will provide your mechanic with a lot of the information he claims Jaguar doesn't publish ( ), such as the resistance vs. temperature chart for the Engine Coolant Temperature Sensor (ECTS) on page 34 of the pdf file:

http://www.jagrepair.com/images/Trai...ual-9-5-01.pdf


Cheers,

Don

 

YOU DA MAN! Thanks Don B! I'll certainly contact my mechanic (if still necessary) once I've digested all this info. I'm always appreciative to get MORE DATA! Thanks again!

 

Yes they are published. Just not in the places your mechanic happened
to reference.

They are published in JTIS complete with pinpoint tests which are the
test procedures for obtaining the readings.

JTIS download links are in the stickies, and it is also available as a PDF
from alternate sources.