Thought I’d document a problem and solution that cropped up on my 2017 F Type R. A few months ago, I got a check engine light (CEL). Used a my Bluetooth code reader and got a couple of codes about accelerator low-position calibration error. Shortly after, I got a restricted performance message and the car was in limp mode.

I used my reader to clear the codes, and all was fine for a week or two. Problem occurred again, and this time as a precaution, I ordered up another accelerator pedal assembly off eBay for around $40. Cleared the codes, was fine again for a few days. Over the next 2 weeks, this problem reoccurred with increasing frequency. Finally a few days ago, once I cleared these codes, they immediately reappeared with the “restricted performance” message and no way to get out of limp mode. Whatever was failing - probably with the accelerator assembly - had finally bit the dust.

So, I decided to swap out the accelerator pedal assembly. Fairly easy job. First, unplug the battery. Then remove the three torx (T30) bolts under the dash and swap out the pedal. I then cleared the codes - which stayed cleared - and did another unplug/replug cycle on the battery.*. Problem is now resolved. No issues and car has been solid for a couple of days. Obviously, the issue was the electronic throttle assembly. I’m guessing the potentiometer got out of range, either due to contamination or wear. I have read of this issue on a few other Jags. FYI.

Edit: Update. I decided to take apart the old accelerator. Pic is below. It uses hall-effect sensors for throttle position. Those are 3 magnets on the pedal assembly. Now, I noticed my assembly was missing one of the torx bolts that holds it together. There was noticeable play in the housing. This is likely the source of my problem. Hall effect sensors are very sensitive to position. The lack of this bolt meant the sensor wasn't properly postioned. Someone had this pedal open in the past, and didn't properly reassemble it. The new pedal I installed fixed this problem, obviously.

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*For those unaware, there’s a nasty bug in the OBD-II port on our F Types. If you plug in any device to the OBD-II port, it puts the car on a permanent-on condition which will rather quickly drain your battery. You know its in this condition as the warning triangle light on the hazard lights button will remain illuminated. The solution to this problem is to unplug/replug the battery. You have to do this anytime you use the OBD-II port.

 

Awesome, thank you for posting the solution.

 

Regarding your comment shown here below;

' If you plug in any device to the OBD-II port, it puts the car on a permanent-on condition which will rather quickly drain your battery. You know its in this condition as the warning triangle light on the hazard lights button will remain illuminated. The solution to this problem is to unplug/replug the battery. You have to do this anytime you use the OBD-II port. "


Does this also apply to when taking the car to the state motor vehicle inspection station for the car's safety inspection?

Thank you!

 

The OBD drain issue isn't "whenever you plug into the port" but when a particular device doesn't close the session correctly. Smog tests apparently will trigger the condition. Mine's been plugged in many times in UK garages and I've never had the drain condition. Please don't peddle misinformation.

 

Respectfully, I didn't peddle 'misinformation". I provided an accurate description of an issue including an indicator of when the issue arises (the illumintated warning triangle), and the solution. This is well-documented right here, and among that documentation is the finding that it results from OBD readers not properly closing out the query with the Jag software. Most readers won't do this. The readers at the dealers avoid this problem, of course, but most others do. I've had this issue everytime an OBD reader is plugged into my car, including the emissions inspection station readers.

 

Sorry but I have to agree with scm, this problem most definitely does NOT occur every time you plug something into the OBD2 port.
At least not on every F-Type.
I for one have NEVER had this problem and I have plugged numerous things into the OBD2 port, most commonly my iCarsoft LR V2 code reader hundreds of times.
Less common plugs I have used are the VAP tool and an ELMs 327 dongle.
Yes it does appear to be a problem with some/most US state based emissions tests but luckily for me there is no such thing in my neck of the woods.

 

I'm from Morris Co NJ as well. The state inspectors in Randolph haven't caused a battery drain 2 of 3 inspections.
Our older OBD scanner hasn't stopped shutdown, either.

The inspector that did, probably didn't shut down the reader (they were rushed). So, it is wise to verify that the HAZARD triangle goes off after 15 - 20 minutes.

PM me if you want to join me with an Adult Beverage while we wait for your light to go off. (Sip, don't chug!)

PS: The GMC dealer 0.5 miles from the inspection station has an F-type in their used car lot.

 

Hmm... I thought this was a universal problem, but now appears to be related to the software in our individual cars, so I'll add my $0.02 here.

First, I bought my car in July 2018 after it was returned to a Jaguar dealership in southern CA (that will go unnamed) under the Lemon Law. The car repeatedly had dead battery issues, the dealership had replaced the battery in the car 5 times during that process but could not figure out what the problem was.

I purchased the car from the Jaguar dealership in West Palm Beach, Florida (who I have nothing but good things to say about) who purchased the car at auction. They did a significant number of upgrades/fixes to the car prior to my purchase including of course, replacing the battery again for the sixth time.

After I purchased the car and became aware of this OBDII issue and the battery reset from this forum, I have watched the red hazard triangle after every OBDII connection closely and can say that without question, every time something gets plugged into my OBDII it requires a battery reset afterwards. I have two different OBDII readers, its happened every time I have gotten the car back from the dealership and it has happened every time I have taken it in for emissions testing.

With the forgoing being said, I still have the sixth battery the West Palm Beach dealership put in may car in July 2018 and it is still working perfectly because of watching the hazard triangle and using the battery reset fix.

 

There was a software update for the older cars that was supposed to mitigate (or lessen) the OBD-II disconnect issue--I don't know how successful it was. I know I never had this issue in my 2018 nor my 2023, including numerous connect/disconnect of tuner devices, Bluetooth code readers, and yearly state inspections at multiple locations.

 

Adding a bit more info for future owners. After a week or so, I got another limp-mode and CEL. This time, the code was for low-input error in the accelerator sensor (for circuit E, see below) I cleared this, and the error would return within a day or two. I hooked up a real-time reading of the accelerator postiion output, and noted that the baseline was reading about 17% open. It would vary by perhaps 0.5% depending on time, temperature, etc, and the code seemed to occur when the baseline reading was on the high side.

Anyway, I got to thinking that these sensors are probably calibrated at the factory. I reassembled my old accelerator (pictures, above) with a combination of epoxy and screws, and reinstalled this into the car. Now, the baseline reading was 14% open. Since I reinstalled this, I haven't had a return of the low-input error CEL and limp mode.

Lesson: the accelerator is a digital device that likely is calibrated as part of initial assembly (and there may very well be a calibration procedure in the Jaguar Shop software, which I don't have access too). Just replacing the hardware may or may not work. It's worth reading out the accelerator position values before replacement, so you have a reference. In my case, there was a pretty substantial difference and this lead to another problem. FYI.

 

Interesting. I’m looking in the repair manual…

So it’s an analog sensor. This is a pretty clever way of ensuring the validity of the position reading.

Here’s a link to the workshop manual…
https://www.dropbox.com/scl/fi/o6d1x...k7yc02pyx&dl=0

 

Thank you for this. The analog output heads to the ECM, where it is digitized. I'm still nearly certain that there's some sort of calibration done as part of all this. I've had 2 separate accelerator modules installed in my 17 R. As noted above, one read 17% baseline, the other 14%. I was getting low input errors with the 17% module.

 

Yeah, I was looking to see if calibration was mentioned, I didn’t see anything.