2007 Jaguar XKR. The coolant temperature sensor at the top front of the engine is leaking. I went to replace it. It takes 1 or 2 minutes in total to complete the job.

With the new sensor in place, the car does not start. The starter spins endlessly. If I put the old one back in, the car starts right up. I have now been to two auto parts stores and tried two sensors. They both are from the brand “Standard” and they both have the part number TX104.

https://www.oreillyauto.com/detail/c...sor/std0/tx104

Both the old and the new sensor are push in, not screw in. Both the old and the new sensors look the same.

I searched the forum and did not see any reference to this problem.

Does anybody have any idea why my car won’t start with the new sensor?

Biff

 

New sensor could be bad. Did you read the 1-star reviews on that site?

 

Maybe. I got one from O'Reilly's and one from Monument Auto Parts. I was thinking the odds of getting two bad sensors was probably small.

BIff

 

With all three sensors on your work bench (so the ambient temp is the same for all), use an ohm meter and measure the resistance across the contacts on each, are they the same?
Guessing the new ones don’t match the original.

 

NTK also makes the sensor. Big name reliable brand. New one works on my '07 4.2.

 

I bought a spare from Jag - resistance was the same with both at ambient temp.

 

panthera999, the part you are showing is screw in. Mine is push in.It turns out that the part listed by many auto parts stores is wrong (https://www.oreillyauto.com/detail/c...sor/std0/tx104). The contact prongs are shorter on the TX107, probably never complete the connection. The correct part number is AJ88655.

Thanks to everyone for all of the help.

Biff

 

Is it easily accessible? Is it near the thermostat. Is there a tool to slide under the rim, that will pry it up?

 

The only commonality (other than something being wrong with the ECU's interpretation of the temp signal) is the sensor ground point at PIS52. But I see that the sensor grounds also go back to the ECU, as well as chassis ground points.

 

Post #7 - it's fixed I think.

 

Yes, it is fixed.

 

What was the fix? Another part, or something else?

 

Post #7 in this thread.

 

Reposting the fix here.

It turns out that the part listed by many auto parts stores is wrong (https://www.oreillyauto.com/detail/c...sor/std0/tx104). The contact prongs are shorter on the TX107, probably never complete the connection. The correct part number is AJ88655.

 

I've added RESOLVED to your thread title for the benefit of the disbelievers.

Many read the first post in a thread and then ignore subsequent replies before posting their own.

Graham

 

A lot of the better You Tube mechanics have posted about "new-out-of-box" replacement parts not working. One guy - Diagnose Dan - scoped a circuit and found pulses present, but looking further, found data polarity reversed at the component. Proved by swapping the two wires with each other. This quality control issue seems to be on the rise; be vigilant about sourcing parts.

 

I was interested to know that the temp sensor was apparently in the start authorization sequence, along with the brake switch and the P/N transmission status etc. Didn't know that an unplugged temp sensor would prevent start.

 

Evidently that would make for a great Kill Switch to avoid theft.

 

I know this thread is a couple years old, but I ran into this same issue with the ECT sensor replacement this Summer on my 2008 XKR. Thank goodness for the sharing of repair sagas by this forum's members.
I replaced most of the accessible coolant hoses (not the valley hoses) as they were 17 years old now. The ECT sensor ,although functional, was a bit of a loose fit in the thermostat housing manifold so replaced it to avoid a potential leak source. My local foreign car parts guy provided a Hella part number 6PT 009 309-781 which appeared identical to the old OEM part.
Good brand right?, so shouldn't be a problem.... WRONG! Engine would crank but not start. So now I'm chasing a some connection or wire that I broke or failed to connect during the cooling hose replacements. No obvious issue found, so looked to the forum for potential causes.
Hat's off to Biff Baxter's thread regarding the replacement ECT sensor problems. Put the original ECT sensor (with new Viton o-rings installed so now a snug fit in the thermostat manifold). Car started right up!!!
As Biff had mentioned a possible issue with the sensor electrical pin lengths not mating with the wire harness connector receptacles, I took a few measurements on the working original sensor and the non-working Hella part. See the attached picture with scribbled sketches. I did not measure the wire harness connector ,but a replacement sensor with connector measures similar to the original part might well work and be substantially cheaper than a Jaguar replacement sensor ($60 or so!). My original part part number in the picture is taken from the part and not the Jaguar P/N mentioned above..
Thanks again, Biff!