Searched the forums but couldn't find a duplicate of what I'm seeing.
My Jag (2005 S-type VDP) has thrown a Gearbox Fault alarm and gone into limp home mode 3 or 4 times in the past few weeks. Each time I pull over, turn the car off, wait 5 minutes and restart. Car drives fine.

My CEL has been on for a while, but the only codes I read on my INNOVA are: P0457 - evap emission system leak fuel cap loose
P0442 - evap emission system leak detected small leak
P0456 - evap emission system very small leak
P1000

I've cleared the codes and after 100 miles or so the same codes return. Haven't had any luck finding root cause on them yet.

My question is:
If I take my car to a dealer, are they able to pull additional codes ? From the transmission for example?
If not, is it safe to assume that these gearbox faults aren't actually being caused by the gearbox since the only codes I am seeing are emissions related?

Thanks as always for the help.

 

Firstly, what is the age and condition of the battery? A failing or weak battery can cause random DTCs to be set and the MIL to illuminate.

Quite often the fault lies with the engine, not with the gearbox. If there are problems with engine performance, misfires for example, the TCM puts the gearbox into limp mode for protection.

You do not mention the number of kilometres/miles on the vehicle. Have the spark plugs or coils been replaced recently?

 

Thanks for the quick reply.
I've had the car a little less than 2 years, and 12K miles. It now has 87K miles.
Just after purchasing the car, I replaced 2 coils due to a misfire CEL and installed a new Bosch battery.
The other 6 coils and all sparkplugs were replaced about 2 months ago, hoping to solve the gearbox fault issue.

Sorry, should have included that detail in the original post.

 

Check and post LTFTs and STFTs to determine if there is a vacuum leak.

 

Hope it's partly the gas cap - another is quite cheap to try.

+1 on watching fuel trims for hints.

 

First time trying to read trims, let me know if this is not what you're looking for.

P0457
Fuel Sys 1 CL
Fuel Sys 2 CL
Calc Load 11%

STFT B1 -5.5%
LTFT B1 2.3%
STFT B2 -4.7%
LTFT B2 0.8%

ECT 192.2F
Fuel 55.3psi
MAP 6.5inHg
Eng RPM 1142
Veh speed 29mph
Spark adv 10.0
IAT 84.2 F
MAF 0.8 lb/min
TPS 4.3%

 

Try hot engine, parked.
At idle.
Then rev to 2500.

So 4 LTFTs.

But you may well have EVAP-type fault(s) as your car has flagged.

 

Will try to collect the additional trim data tomorrow.

From the questions so far, is it safe to assume that the gearbox faults may not have anything do with the gearbox? I haven't been driving the jag very much out of concern for doing serious damage / being stranded.

 

Discovered that I bought the wrong code reader. My INNOVA 3150d apparently only reads freeze frame data after a CEL. Should have done more research.
Below is the FF data collected after I cleared the previous codes and drove around 100 miles. Codes for P457, P442, P456 are all on. All are evap emissions related.

Can anyone glean anything useful about my gearbox faults from the below?

P0457
Fuel Sys 1 CL
Fuel Sys 2 CL
Calc Load 43%

STFT B1 1.6%
LTFT B1 1.6%
STFT B2 3.1%
LTFT B2 3.1%

ECT 186.8
Fuel 55.3psi
MAP 22.7inHg
Eng RPM 1565
Veh speed 46mph
Spark adv 28.0
IAT 48.2 F
MAF 4.0 lb/min
TPS 14.9%

 

Go with workshop manual for those codes but don't omit the 0 as it's required.

 

Update on the P0457, P0442, P0456 codes. My mechanic performed a smoke test and could not find a leak anywhere. His thought is that since the OBD codes are for "very small leak", this means that IF there is a leak, it's either on top of the gas tank where it's very hard to see or one of the valves in the system is leaking by. I replaced the Evap emissions canister purge valve resonator about a year ago as per https://www.jaguarforums.com/forum/s...76/#post277647

Any suggestions for the next most likely suspect? Maybe the Canister close valve?

 

Since your codes are all emission vacuum leaks let me suggest to check the fluid level in the transmission next.

Has it been checked or changed? Low fluid level can cause many problems and will damage the transmission. Are you aware of the sealing sleeve that should be replaced when servicing the transmission?

About your existing codes. Also look at the plastic canister under the hood on the drivers side cam cover. That plastic canister has been known to crack. You might even hear the leak. But check there and also the passenger side valve mounted on the cam cover. All those lines are plastic/rubber and can crack and leak.
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check brake booster cable attached to a secondary elbow into back of intake on engine was root cause of my issue in my 2003 str is common problem in these models and will cause intermediate gear box fault / limp mode

 

I suspect that at least one transmission code was generated when the gearbox fault occurred but your scanner may not be able to read it. iCarsoft LR V1.0 can read transmission fault codes plus a lot more. LR V2.0 is supposed to be even better.

 

hijk has NOT posted since this last one 5 years ago.

I don't think hijk cares or is going to reply. (just a feeling I have)

 

What Motorcarman said...

 

Only saw the age of the thread after I posted. Yeah, the OP pulled a disappearing act.

 

Just a note but the problem is the brake booster vacuum hose NOT any cable attached to the SC elbow.
Yes old thread with a MIA OP!
It's a shame we don't get much feedback about the final solution or outcome. Heck he might have just sold or junked the car.
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