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Richard, Jaguar Technician
Category: Jaguar
Satisfied Customers: 15512
Experience:  12 years at a Ford/Lincoln Mercury and Jaguar dealer as technician and shop foreman.
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I have a 2004 VDP. I have intermittently received the messages

Customer Question

I have a 2004 VDP. I have intermittently received the messages eng. system fault, DSC not avail and park brake fault and experienced the car going into limp mode. I put a scanner on it and it read code P1251. After that, the messages went away and the car came out of limp mode but restricted performance showed up. After a few more starts the car went back to its original problem but with restricted performance added to the messages.
Submitted: 2 years ago.
Category: Jaguar
Expert:  Richard replied 2 years ago.
Hello and welcome to
We may have a problem with the throttle relay or front fuse box. The throttle relay is internal into the fuse box. We need to check power to fuse #24 (20 amp) when the problem occurs. Sometimes I see corrosion on the bottom of the fuse box connectors.
Customer: replied 2 years ago.
There is no signs of corrosion and I changed the #24 fuse before I sent my message. I'm not sure how to check for power going to the fuse box. Will you be able to tell me how to check for this?
Expert:  Richard replied 2 years ago.
With a digital voltmeter meter set it to dc volts. Place the black lead to the body and the rest lead to both sides of the exposed terminals at the top of the fuse. Do this with the ignition on or engine running.
Customer: replied 2 years ago.
Is it possible that the MAF may need to be replaced with that code (P1251)?
Expert:  Richard replied 2 years ago.
No it is usually not a bad MAF.
Customer: replied 2 years ago.
Hey Richard,
I took my car the Jaguar dealer because I just couldn't find anything wrong with it myself. Well, they quoted me $25k to fix it because according to them it needs a new fuse box, a new MAF, MAF sensor, a new throttle body and a new transmission. I don't think this is accurate and I'm inclined to believe your diagnosis is more accurate. What do you think? Have you heard of this before?
Expert:  Richard replied 2 years ago.
Wow that is a lot. I can see possibly the fuse box as that is what we discussed. Unfortunately without knowing how they determined all this it is hard for me to say.
Customer: replied 2 years ago.
Hi Richard! I was told that my car has two throttle relays. One is 20v and the other is 40v. Can you tell me where to find these relays in the fuse box? What R number corresponds with them?
Expert:  Richard replied 2 years ago.
There is one throttle relay but it is part of the circuit board in the engine fuse box.
Customer: replied 2 years ago.
I can't tell you how much I appreciate your help. I ordered a fuse box and replaced it in my car and now my car is running normal again. The only issue I have now is that the check engine light is still on, but I think that's because the system needs resetting. I'm a bit angry because I told the dealer that I just wanted them to replace the throttle relay, but instead they charged me to diagnose each individual error message, hence they're figure of 25k to fix it and $400 in diagnostic fee.
Expert:  Richard replied 2 years ago.
I am very glad to hear the vehicle is back on the road. We should clear the light with the scan tool to see if it returns. You can use a tool from your local parts store to do this.
Customer: replied 2 years ago.
Hi Richard,
So I cleared the check engine light, but shortly afterwards it came back on with the message restricted performance. I hook the scanner to it and it gave me two codes p0171&p0174. I checked out the engine and saw that there was a hole in the airflow hose near the meter reader. I replaced that, cleared the check engine light and now I'm getting the same messages and the same codes. Do you have any suggestions? Could this be the MAF sensor?
Expert:  Richard replied 2 years ago.
Yes if there is no more air or vacuum leaks then yes this is most likely a bad mass air flow sensor.

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