Rough idle on cold start and code P0442
#1
Rough idle on cold start and code P0442
OK, would any body be able to tell me what code P0442 is? It is probably related to the rough idle on cold start. (I found mention of this code in another thread, but it was not identified). Car starts right up and runs smooth for a few seconds, then the idle drops down below 1000rpm and is rough for a few seconds to a minute, then smooths out. Thanks in advance
Edit: Oh I guess it might help if I mentioned this is an 07 XKR
Edit: Oh I guess it might help if I mentioned this is an 07 XKR
Last edited by liquid-chris; 04-10-2014 at 11:40 PM.
#2
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liquid-chris (04-11-2014)
#3
Weird; I can't find P0442 in the 4.2 workshop manual, but as JagV8 says, the 5.0 manual says it's an evaporation control system leak. Diagnostic actions:
1. Inspect / refit filler cap after smoke test (inspect filler neck for correct fitment to pocket so that filer neck protrudes)
2. Run engine at idle; Using the manufacturer approved diagnostic system, run Purge Valve Self Test (to clean the purge valve)
3. Check that the DMTL module wiring connector has been installed correctly and that the seals around the connector body and individual wires are in good condition
4. Check all fuel system connections are correctly installed and secure
5. Visually inspect purge canister, purge pipes, fuel tank and filler neck for any
obvious damage
6. Try isolating the purge valve by fitting a blanking plug to the purge pipe
7. Carry out a smoke test
8. Replace the DMTL module
2. Run engine at idle; Using the manufacturer approved diagnostic system, run Purge Valve Self Test (to clean the purge valve)
3. Check that the DMTL module wiring connector has been installed correctly and that the seals around the connector body and individual wires are in good condition
4. Check all fuel system connections are correctly installed and secure
5. Visually inspect purge canister, purge pipes, fuel tank and filler neck for any
obvious damage
6. Try isolating the purge valve by fitting a blanking plug to the purge pipe
7. Carry out a smoke test
8. Replace the DMTL module
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liquid-chris (04-11-2014)
#4
This forum, you guys, are going to make owning my first Jag a lot easier to deal with. I might have above average mechanical aptitude, however, I am certainly no Jaguar tech. I bought the pdf of the manual, but could not find P0442, and have to say, if all Jag manuals are written this ambiguously and convoluted, it is amazing any of us can work on them without just doping off the car and our paychecks at the dealer. I am in the San Francisco bay area. We have four dealers within a 50 mile radius. All have terrible reputations for misdiagnosis and being very proud of their parts. Need to find a good independent shop for when I find things I am unable to tackle myself. I saw a thread asking that question, I subscribed, but no recommendations.....
Thanks again for the help gentlemen. You remain my best option.
Thanks again for the help gentlemen. You remain my best option.
#5
The biggest PITA, as you can see from the diagnostic actions, is that a lot of stuff requires (or is made a hell of a lot simpler by having) the proprietary Jag diagnostic system. There are some third-party OBDII readers that work with 'semi-official' outdated versions of the Jag software, but the whole thing is a bit too kludgy for my liking.
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liquid-chris (04-11-2014)
#6
The biggest PITA, as you can see from the diagnostic actions, is that a lot of stuff requires (or is made a hell of a lot simpler by having) the proprietary Jag diagnostic system. There are some third-party OBDII readers that work with 'semi-official' outdated versions of the Jag software, but the whole thing is a bit too kludgy for my liking.
Yeah...at least the five digit code gets me in the neighborhood. I hate the thought of paying the dealer $120 to tell me I need to replace my air cleaner.
#9
Its part of the EVAP (fuel evaporative sysyem) sits above the differential by the charcoal canister. If I understand correctly it puts a very slight pressure in the fuel system and somehow self tests for leaks. Not too uncommon to fail. Problem is it is a real pain to get to, from what I've heard you have to move the diff out of the way to access.
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JaggyBoii (03-16-2024)
#10
DMTL = Diagnostic Module Tank-Leakage. From the manual:
The DMTL system is a legislative requirement for NAS vehicles. The DMTL system periodically checks the EVAP system and the fuel tank for leaks when the ignition is switched off. The DMTL system comprises the previously described components of the EVAP system with the following additional components; a DMTL pump and a DMTL filter.
The DMTL test is performed after the engine has stopped following a 10 minute run, providing that the vehicle fuel tank is between 15 and 85 percent full, the ambient temperature is above 0°C (32°F) and less than 40°C (104°F) and the vehicle was not started for at least 3hrs prior to this run.
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Jumpin' Jag Flash (01-13-2021),
liquid-chris (04-27-2014)
#11
It's baaaaaaack. Okay I had five days with no MIL, the rough idle on cold start was definitely worse. But now the MIL is re-lit (code P0442 again). So I know the DMTL failed a self test. It was replaced and now it does not fail the self test. The rough idle on cold start is worse. So with my limited understanding of the EVAP system, it has to be something between the DMTL and the purge valve (that was supposed to be a question and not a statement). Other info that might be pertinent: I purchased this car two months ago, 07 with 9k miles. It sat for a year prior to purchase. It still runs like a bat out of hell. I am a Sagittarius with blue eyes and my favorite color is blue.
I am planning on leaving on a trip tomorrow (750 mile round trip) and was looking forward to driving the car. Take the car? Don't take the car? Ignore the MIL until I get back?
I am planning on leaving on a trip tomorrow (750 mile round trip) and was looking forward to driving the car. Take the car? Don't take the car? Ignore the MIL until I get back?
#12
Maybe they didn't install it correctly, or damaged a seal during installation, and a small leak has developed. I'm not sure how this would relate to the rough idle, though - that sounds like a coil or plug problem. But I'd expect to see some DTCs relating to the misfire coming up on your code reader.
It may be time to get a dealer to check the codes, to see if anything else is showing that your generic reader isn't picking up.
But if it's running OK once it warms up, it's probably fine for a road trip.
It may be time to get a dealer to check the codes, to see if anything else is showing that your generic reader isn't picking up.
But if it's running OK once it warms up, it's probably fine for a road trip.
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liquid-chris (05-01-2014)
#13
Maybe they didn't install it correctly, or damaged a seal during installation, and a small leak has developed. I'm not sure how this would relate to the rough idle, though - that sounds like a coil or plug problem. But I'd expect to see some DTCs relating to the misfire coming up on your code reader.
It may be time to get a dealer to check the codes, to see if anything else is showing that your generic reader isn't picking up.
But if it's running OK once it warms up, it's probably fine for a road trip.
It may be time to get a dealer to check the codes, to see if anything else is showing that your generic reader isn't picking up.
But if it's running OK once it warms up, it's probably fine for a road trip.
#14
Enjoy the trip - but make sure your AAA membership is up to date, just in case
For future investigation, one source of rough cold idling is a break in a wire that closes up when the engine heats up & the wire expands. I had a problem like that in a plug lead once - it was a bugger to find. It will really help a lot if there's a code indicating "misfire on cylinder 3" or some such, so you know where to look.
For future investigation, one source of rough cold idling is a break in a wire that closes up when the engine heats up & the wire expands. I had a problem like that in a plug lead once - it was a bugger to find. It will really help a lot if there's a code indicating "misfire on cylinder 3" or some such, so you know where to look.
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liquid-chris (05-01-2014)
#15
Take the trip. This is a very minor code and does not affect anything but evaporative emissions. Just be aware several people on the S Type list have chased this one for a long time.
As JagV8 said this is a "small" EVAP leak. There are also codes for the large "Evap" leak which is MUCH easier to find. Many times the P0442 is a failed gas cap or a not proper latched fuel cap. Have you checked this yet?
It may take a dealer to do the smoke test to find it. From what you posted I think they just changed a part on you and did not troubleshoot it completely.
Can you take it back to the mechanic as the repair is so recent? I think it's his responsibility. With $618 at stake I would sure bring it back.
I would like see a picture of the part they changed as that is not on the earlier cars and I was unaware it was added.
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As JagV8 said this is a "small" EVAP leak. There are also codes for the large "Evap" leak which is MUCH easier to find. Many times the P0442 is a failed gas cap or a not proper latched fuel cap. Have you checked this yet?
It may take a dealer to do the smoke test to find it. From what you posted I think they just changed a part on you and did not troubleshoot it completely.
Can you take it back to the mechanic as the repair is so recent? I think it's his responsibility. With $618 at stake I would sure bring it back.
I would like see a picture of the part they changed as that is not on the earlier cars and I was unaware it was added.
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liquid-chris (05-01-2014)
#16
Ohhh yeah I'm bringing it back to the same dude as soo as I get home. And he better hook me up. Yeah, first thing I did was check the cap was on tight (I don't have a way to vacuum test the cap, but I know they do that when they're smogged). Yeah, this is sounding like it has smoke test written all over it.
#17
#18
Okay so last Thursday the 0442 code came back. Friday morning I cleared the code before heading to Oregon to visit mom (700 mi round trip). Code has not come back? Prior to replacement of DMTL it would return the next time I started it (or definitely within 3 times). I guess I'll just have to see. Might be like TFlan says...just gonna be something I chase.
Car ran fan-freakin-tastic. Wow.
Car ran fan-freakin-tastic. Wow.
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Ngarara (05-05-2014)
#19
If it keeps coming back, I think you have a case for asking the Bacchus people to take another look, because they clearly didn't test/diagnose it fully. Just changing the DTML pump hasn't solved it - in fact, it may not even have been necessary. Ask them if they smoke-tested it, as they should have done.
#20
Read post #10 as to why this code might take some time to come back. The problem might be there for quite a while and not show up til the requirements are met for the car doing a test on the system.
I had a car with this code and had to drop the fuel tank to tighten up a vent line clamp on top of the fuel tank. Not a Jaguar though.
I had a car with this code and had to drop the fuel tank to tighten up a vent line clamp on top of the fuel tank. Not a Jaguar though.