Hey there,

I have a 2002 3.0L X-Type with about 88,000 miles on it.

In the past few weeks I've experienced the CEL warning with the occasional "cruise control unavailable" warning. I pulled the codes which were P0171 and P0174 which i researched and found to be a probable vacuum leak. Tuesday of last week i suddenly recevied the alternating "engine system fault & transmission failure" warnings in addition to the CEL & cruise warning. The vehicle seemed to be in a severe limp mode which would only allow me to drive about 7 mph.

I immediately turned off the car and then re-started. No warnings aside from the CEL. A few miles down the road while at a stop light the engine/transmission warnings appeared again. Once again, a re-start cleared the warnings and I was able to make it home.

The following day i did the following. I replaced the IMT o-rings (both upper and lower) as well as the pcv tube with the factory "ribbed" version. I noticed that the check valve on the Brake Booster line was slightly corroded but I didn't hear any leaks. I currently have one on order but won't have it until the 2nd of February.

After replacing the IMT O-rings and the PCV tube I disconnected the battery, reconnected it and checked the fault codes. I received the following: P0171, P0174, P0121, and P0420. I then cleared all codes. After clearing all codes the car seemed to operate normally for a good day or so. Then the CEL returned as well as the occasional "cruise unavailable" message. I assumed it was just my brake booster line needing replaced or possibly the MAF sensor. Then the engine/transmission faults reappeared.

As of this morning the engine transmission faults were appearing on a regular basis so I went to check codes again and received the same 4 codes. I reset and my CEL is gone and I'm not receiving the "cruise unavailable" message but I am now receiving the Engine/Transmission fault errors until I do a restart.

Does anyone on this forum have any insight to lend? I'm not sure what else I can check on the vehicle or what components need to be looked at and/or replaced? It's obviously very frustrating and I'd like to avoid the dealership at all costs

I've read in some other threads that it could be the throttle body but I'm curious if anyone has any other ideas.

Thanks a ton in advance for any input. I'm at wits end with this mess!!!

If you need any other information please don't hesitate to ask....I'll gladly reply.

 

for your cars pleasure

Did you find any vacuum leaks? Do a thorough evaluation, and put it thru a few more driving cycles before thinking nothing was improved. And of course, report back.

 

Well I've done as thorough of an inspection as I know how. I'm not certain where else to look in all honesty.

As far as putting it through a few more driving cycles I've done so and the engine/transmission error is appearing far more frequently now. I would say 3 out of 4 starts produce the error. These would be considered warm starts I suppose. I don't believe that I mentioned that when the errors DO appear the car has a very high idle close to 2000 rpms whether in neutral/park or in drive.

When the errors are not present the car drives like normal....no problems what so ever.

 

Hey,

I was going to create my own post, but I think it may be best if I post what I know with your problem. Two heads are better than one. I hope you don't mind, if you do let me know. My car is having the exact same issues untill it died on me and won't go past 3rd gear.

Jaguar symptons (2002 X Type 2.5):
1) The transmission kept overflowing from my transmission breather. I believe know I over filled it. I am using Castrol Multi Vehicle Import transmission fluid. I did my research and seems to be ok.

2) I ran the generic OBD II Scanner and recieved these codes.
P0171 Bank 1 Combustion Too Lean
Possible causes:
Leak at Air Intake
Faulty Fuel Filter
Fuel injection
Fuel Pump/Low Fuel Pressure
Faulty Oxygen Sensor Wiring
Exhaust Leak
Faulty ECM

P1603 EEPROM Malfuntion
No Info Just Transmission

P0174 Bank 2 Combustion Too Lean
Possible Causes:
Leak at Air Intake
Faulty Fuel Filter
Fuel injection
Fuel Pump/Low Fuel Pressure
Faulty Oxygen Sensor Wiring
Exhaust Leak
Faulty ECM

P0720 Output Shaft Speed Sensor Circuit
No Info

P1111 Intake Air Temp Sensor circuit High Voltage

P1603 EEPROM Malfuncton
No Info

Diagnostic Info:
Engine Coolant Temp 204.80 F
Fuel Rail Pressure 55.69447 psi
Intake Manfold Press 11.25 inHg
Engine RPM 3,457.75 rpm (Only the switch is on)
Speed Sensor 16.16 mph
Intake Air Temp 104.00
Air Flow Mass Sensor 2.95 ib/min
Throttle Position 14.90%

3) The Jag was stalling and not moving forward, I changed the fuel filter and it fixed the stalling.

4) The car will not go past 3rd gear, I did research assumng I need to rebuild mytransmission.

5) I came across a site about Jatco transmissions that read if your transmission is not shifting properly often the result of a computer sending incorrect signal due to a fault sensor, or the transmission is not reacting to the computer command because of a bad connection or defective solenoid pack. These connections can be corrected while the transmission is in the car less money than a complete overhaul.

6) I was reading there is a connection solenoid in the J Gate that controls 1st, 2nd, 3rd gear. I don't know where this is located,I am researching. I will post pictures of the electrical coponents that I located and any info is appreciated.

7) I found a transmission rebuild kit for $224.00 but obviously this is a project on it's own so I will check the electrical before I go further.

Im' not trying to take time from your problem, but have realized all the Jaguars have the same problem and same fix. I hope my info helped.

 

I don't see any trans codes here at all. The p0171, p0174 if hard faults will cause cruise unavailable but not usually limp mode unless you are hammering the engine to high rpm at wot. At that point the ECM will restrict performance to avoid engine damage from the lean condition and the revs wont come above about 5000. Other than the wot cut out the car should seem to drive normally with perhaps a slightly rough idle and possible stalling if the pcv hose is split wide open. The p0121 will be instant restricted performance, limp mode. This code is a throttle position code and any throttle codes in fly by wire will be automatic limp mode ie 7mph. We don't want any Toyota type problems with the Jag now do we. 2 questions, are you reading all available codes? What type of scan tool? In other words will your scan tool read manufacturer codes or just generic? You may have CAN network codes ECM to TCM but a generic reader wont pick them up. I would worry most about the p0121. Several causes though, just because it is a throttle position code doesn't mean it couldn't be something else. More info available when more info received. What codes do you get now?

 

Okay....so here's the most recent developments. Right before my original post this morning i had driven the car about a total of 25 miles in two separate trips. 1st trip the car gave me issues twice. Second trip another two instances where it went into sever limp mode. I attempted to drive a third time and it consistently gave me the engine/transmission code on 5 starts so I parked it. Once again no CEL was lit up, only receiving the occasional aforementioned errors.

Car sat for about 8 hours without being touched. I arrived home and decided to *attempt* take it to Autozone to check fault codes. Car started up no problem but now was displaying the CEL. Drove it to Autozone and here is what I received for errors. BTW i used an Innova 3120 Can OBD2&1 reader. Unfortunately this is the only one I have access to aside from the dealers.

I checked the codes with the car running and here are the three error codes: P0121, P0171, and P0174 (p1000 was also displayed but seems irrelivant)

Not sure if it's relavant or helpful but here's the "freeze frame" data:

FUEL SYS 1 OL
FUEL SYS 2 OL
CALC LOAD (%) 26.2
ECT (F) 163
STFT B1 (%) 0
LTFT B1 (%) 10.9
STFT B2 (%) 0
LTFT B2 (%) 10.9
FUEL PRES (PSI) 54.8
MAP (INGH) 11.8
ENG RPM 1161
VEH SPD 0
IAT (F) 125
MAF (LB/MIN) 1.461
TPS (%) 9.4



I then shut the vehicle off and rescanned the codes with the ignition on. I only received a P0121 and a P1000....this was without clearing codes.

I then cleared codes and scanned once again. Now i receive no codes aside from P1000.

This entire trip was around 15 miles and from a cold start i received no engine/transmission errors, and no cruise unavailable error. All that seemed abnormal was a CEL and a very slight rough idle. No limp mode at all.

As stated when i was first experiencing just the CEL and cruise not available i replaced the pcv hose and IMT o-rings....both of which seemed fine prior to replacement. I'm still awaiting the Brake Booster Hose to replace it. I did experience the regular limp mode and/or bucking if I was trying to press the engine beyond 3000 rpm but now the issues have seemed to worsen.

 

Delete 1

 

Hey,

I am not a Certified Tech, but the mechanic to my Jag. Don't mention it's not running and we will be fine. Ok my Jag was doing the same thing, bucking and I thought it was serious. I changed the fuel filter on my to do list and it runs fine. The filter was $8.00 and needs to be changed once a year anyways. I am considering buying a better OBD II in order to properly diagnos the Car. Don't give up your on your way to being a Jaguar Expert only because it's your car. It's little things but the Jag are tempermental and you have to be the expert. I think if you fix all your
air leaks then you need to consider fuel flow for codes P0171 and P0174. The other code I have no info. Do remember I am not Certified.

 

What are the last 6 digits of your VIN number? In the mean time you could unplug the throttle position sensor at the throttle body and check for water, corossion etc. and reconnect to see if it makes a difference.

 

fuel filter was replaced two months ago so it seems to be working fine.

last 6 of the vin are C56239

I'll take a look at the TPS tonight and see what I can find, if anything.

 

Car is platinum correct? The last time this car was in for warranty work was at 34k miles. The transmission was replaced at 22,668 miles which would explain why the trans serial number didn't match for recall. I would still check the throttle position sensor for the p0121 code. All recall and service actions were completed on this car. The 40k free maintenance was skipped but since the last time it was at the dealer for warranty was at 34k that would seem reasonable.

 

Im' doing my HW since I have the same issues Im' posting for your Info:

Failure modes
Before drive by wire technology was introduced, if a throttle stuck open you could generally put your toe under the accelerator and lift up. Occasionally after servicing or repair, the wire or cable between the accelerator and throttle would not be correctly reinstalled causing sudden acceleration. However, with the ETC, the movement is all done by electronic controls moving an electric motor. But just moving the throttle by sending a signal to the motor is an open loop condition and leads to poor control. Most if not all current ETC systems have a closed loop system whereby the ECU tells the throttle to open a certain amount according to an algorithm based on the geometry of the throttle. Then, if due to dirt build up in the throttle bore or a damaged TPS a signal is sent from the TPS to the ECU, the ECU can make appropriate adjustments to compensate, though it might result in surging, hesitation or uneven idle.
There are two primary types of throttle position sensors: a potentiometer or a Hall Effect sensor (magnetic device). The potentiometer is a satisfactory way for non-critical applications such as volume control on a radio, but as it has a wiper contact rubbing against a resistance element, dirt and wear between the wiper and the resistor can cause erratic readings. The more reliable solution is the magnetic coupling that makes no physical contact, so will never be subject to failing by wear.
This is an insidious failure as it may not provide any symptoms until there is total failure. All cars having a TPS have what is know as a 'limp-home-mode'. When the car goes into the limp-home-mode it is because the accelerator and engine control computer and the throttle are not talking to each other in a way that they can understand. The engine control computer shuts down the signal to the throttle position motor and a set of springs in the throttle set it to a fast idle, fast enough to get the transmission in gear but not so fast that the car cannot be stopped by the brakes.
Recently, ETC is suspected to be responsible for some incidents of unintended acceleration in Toyota and Lexus vehicles. This is fiercely disputed by Toyota, who blames unintended acceleration on owners, weather mats, and most recently defective gas pedal.

http://en.wikipedia.org/wiki/Electro...rottle_control

 

Real_tek thanks for the info. Yes the car is platinum and I was not aware of the transmission replacement. I purchased the car with just over 50k on it and it's run great until this little incident.

Here's the most recent development with my situation:

I finally received the Brake Booster Line and was able to replace that this evening. I haven't been driving the car for the last week so I decided to give her a whirl after I installed the new part.

Fired her up and let her idle up to normal temp. It's almost freezing temps here. Idle was normal, no CEL, no Cruise Unavailable, no Engine/Transmission Failure notifications. Drove for about 5 miles and still no notifications so I thought all *might* be well....until the enging/transmission failure notice came on while cruising at about 40mph. Suddenly went into severe limp mode again. Fortunately I was close to home so I got her back to the shop. Turned the car off....then back on....no notifications. Tried that about 7 times and never received a notification or a CEL. Now i've let her idle for a good 15 min....once again, no notifications or CEL.

I installed the part late this evening so I could not make it to autozone to borrow a code reader before they closed. I'm guessing I will probably see the same P0121 code that keeps rearing it's head. I was able to check the two connections on either side of the throttle body and they looked clean. No corrosion, broken wires, etc.

So short of replacing the Throttle Body, are there any other ideas? I'm not sure how clearing the ECU works....I'm assuming the basic OBD readers don't clear anything major. Is it possible that the ECU just needs to be re-set by the dealer or is it more likely that something more significant is wrong. I'm sure it's more likely the latter but I'm trying to be optimistic

Thanks for everyone's input....I'm about to go grey before I'm 30!

 

The ECU is protecting the Car by putting it in Lymp Mode, if you clear the code the Throttle problem is still there. I feel your pain you like your car. I searched for OBD II that would give me all the codes to the vehicle including sensors. Cost about $450, I think if you to take it to the dealer it's about $220. Maybe consider taking it to the dealer and getting the codes so you can fixthe problems yourself. My Jag was doing the same thing untll it stopped running and won't go past 3rd gear. Im' saving for the tranny shop, so I will be ready with cost. Best I can do wish you luck. Have you searched the Jag Forum for the code alone and if nothing comes up post a new thread only for that code. So we have more info when that code appears on our car.

 

When you can get it scanned let me know if the P0121 comes back. That code is by far your biggest concern at this time as that code will put car into instant limp. The throttle position sensor is not available from the Jag dealer seperately from the throttle body. That's not to say you may not be able to find one aftermarket or at a salvage yard.

 

Okay, got the car scanned today. Same story really. Started the car and all was normal...no fault codes, errors, or CEL. Then drove about five miles to Shucks to read the codes. Car went into severe limp mode with the engine/transmission failure. Pulled over, restarted, and all was like normal. Probably happened another two times in that five mile span. Got the code reader and had the same codes come up. P0171 P0174 P0121 P1000.

Cleared all codes and left. Same symptoms returned almost immediately. The only thing that was different this time around was that while in "severe" limp mode the Jag actually allowed me to make it all the way to about 30MPH and get up to 3rd gear. It was still very limited but I had a long stretch of road to go before I could safely pull over. Previously I could not travel any faster than about 7MPH from a stop and now it allowed me to almost 30. Restarts were seemingly less effective this go round. The engine/transmission fault would re-occur much quicker and more frequently.

I'm assuming that I'm looking at replacing/rebuilding the throttle body. My question is this. I realize that the TPS/TB are one unit from the dealer. Can you replace the TPS only if I find a used one? Is it just "plug and play" or more labor intensive that that? My mechanical ability is about a 7 out of 10 so I'm curious if I could do it myself. If I get a used one would I be better of just replacing the whole unit? Also, is the TPS a combined unit on either side of the TB? I see components on either side of the Throttle Body and I'm unsure of what each is respectively.

Thanks again for the help. Any suggestions on finding someone to rebuild one or any idea which years of X-Type (or other models) may be compatible with my vehicle?

 

Two months ago I bought a 2004 X-Type with 40k miles on it. I love this beautiful car, however...

Two weeks ago my wife and I drove it to a restaurant. When we went to leave, I started the car and the check engine light immediately came on. I put the car into gear and the drive train light came on... instant limp home mode. I got about a half mile down the road and determined there was no way I was going to drive home at 10 mph. I pulled over and shut the car off... popped the hood and could not find anything obvious that was wrong. I started the car up and both lights went off and drove home fine. Later that day, I started the car up and drove maybe 20 miles and it went back into limp home mode. I drove the car to the dealership the next morning. They found code P0121 (throttle position sensor) but said they couldn't fix it and it would have to be taken to Jaguar. I had the car towed to Jaguar and they checked it over but couldn't get any codes off of it since the dealer I bought it from had cleared the computer. They did say the IMT o-rings were leaking and they charged me $400 to replace them.

The car drove fine for two days, then repeat the above story about five more times! Eventually, the car would go into limp home mode as soon as I started it, not just when it was warmed up. I took it back to Jaguar, they read the codes as a P0121 and said the throttle body would have to be replaced for $2k.

I towed the car home and began researching the throttle body problem myself. I found a place online (partsonnet.com) that sold me a 'used' throttle body assembly and gasket for $550. I figured I would be better off saving some money and doing it myself. I got the part yesterday and installed it in about an hour (I'm no mechanic). I started the car up and it seems to run better than when I bought it. I drove it about 30 miles last night and then let it run for 30 more minutes at the house. I restarted it several times and so far so good. I'm sure hoping this has resolved my problems!

 

I'd like to ask one thing, were you guys using premium fuel of 93 octane or were you using a lower octane? I'm just wondering if useing a lower octane would cause this problem with the TB senor. I use both a lower octane when I'm on the highway and a higher octane when driving around town. My 02 x-type doesn't have any problem, just wondering if I may be causing one. Thanks

 

I have only had the car for two months but I have always used the high grade gas because that's what was recommended. The car is immaculate and the engine looks brand new like the previous owner took very good care of it. Even when I removed the old throttle body, it looked like a new part - no dirt, no grime.

 

I get great gas milage which ever way I go. With the higher octane or the lower, I know that the higher octane is what I'm suppose to run. But at this point with no problems I see no reason to stop doing what I'm doing. I know that there's suppose to be a high octane senor, but I can't find it in any of the schematics that I've looked at. So at this point there have been some things people have told me and things people have said (not here, so far), that didn't make sense so I followed through till I've found the answer. But asking questions is the way to have a happy car, LOL. So far mine is happy I'm a 4 month 1st owner of my Jaguar.