I have a 2006 Jaguar X-Type stuck in limp mode!

I just replaced the alternator, and the cars voltage is now fixed, but the check engine light is on and I can't accelerate past 15 mph (I didn't have this problem before the alternator replacement). The car idles fine and the alternator has no issue charging the battery

I've tried

• Cleaning MAF Sensor
• Hard resetting battery
• Checking voltage

I've ran ODM codes and got these in return

• P1638 (CAN Link ECM/INSTM Circuit/Network Malfunction)
• P1111 (Intake Air Temperature (IAT) Sensor Circuit Intermittent High Voltage )

Any advice would be appreciated, I'm out of ideas!!

 

P1111 is a status code (you want) that shows the various OBD monitors (all connected with emissions in some way or another even if tenuously) have run fully and are happy.
P1638 - Are you certain you plugged everything back in securely & earth points are fully secure ?

 

Can you get us the approximate mileage, drive train info etc...?
Other than the check engine light, are there any other lights on the dash?

with the car off, turn the key all the way forward to energize the dash. Are the ABS DSC and Brake warning light on?

What does the car idle at?
In neutral, does pushing down on the gas pedal raise the idle?
From a dead stop, what happens if you floor it?
Does the car seem to be starting off in the correct gear, and not fourth?
Does the car get up to about 2000 rpm then retard and stumble hard?

We look forward to your reply.
Ronk

 

The car has about 75,000 miles on it and it’s an AWD drivetrain. Other than the check engine light, there aren't any other lights on the dash. The Check engine light actually stays off when I clear the codes, but it comes right back the moment the car lurches after hitting about 15 mph.

​With the engine off and the dash energized, the ABS, DSC, and Brake warning lights are not on—the only ones showing are the check engine, oil, and battery lights.

​It idles at just under 1000 rpm. In neutral, pushing the gas revs the engine and the rpms increase perfectly smoothly. It also feels like it's starting off in the correct gear rather than fourth.

​When I floor it from a dead stop, the rpms shoot up quickly but the car only slowly gains speed until about 15 mph. Once the rpms hit 3000, the car suddenly lurches forward and back hard. At that exact moment, the check engine light and a "gearbox fault" signal both pop up. The gearbox fault clears itself once I turn the car off, but I have to use an OBD tool to get rid of the CEL.

​I also checked the voltage and it's reading 15 volts while running and 12.9 volts when off. I’m a bit concerned the new alternator I installed might be faulty, but the car sounds good and isn't showing any other electrical or charging issues—just these problems when I'm actually driving.

Thanks for any help! I really appreciate it

 

Are the idle revs typical for that engine & car? They sound high but I don't have that car.

Idle LTFTs should be below 5 - are they?

 

DSC error and possible work around

I was looking into how to disable the red gear box and stuck in 4th limp mode. I came across a bulletin that stated if you hold down the DSC button for 10-15 seconds it would disable it. I am not near the car this week to try it, so I figured I would toss it out before I forgot about it.

Has anyone tried it or know more about it?

Ronk