Started the car up this morning to go out for a smog check so I can do a title transfer and register it but the above lights all came on. I did some searches but they all seem to indicate that just the lights came on with no corresponding engine issues. Oh mine there is very little power. When I put it in neutral the revs go up to 1,500 and then back down. If I push all the way down on the gas it kicks in first gear and the power seems to be there until I life my foot off. In most of the threads regarding the lights the answer seems to be the low battery. I don't want to risk driving at 5 mph to the closest store to have them test the battery and my meter has managed to loose itself somewhere in my garage. Should I just go get a new battery and see what happens or is there something else I should be looking at first?

Joe

 

I just went out to pull the car into the garage to check the battery date and now there are no messages on the dash but the check engine light is still on.

Also, I saw in some of the threads that a regular OBDII will not work a Jaguar. Is that correct?

Joe

 

Year and model will help a lot.

Yes, a cheap-o OBD2 reader will work on a Jag. Any car, for that matter. All it will give you are the "generic" OBD codes, which is what you'll encounter most of the time. It will not do anything manufacturer-specific. For that you'll need a better scan tool. But for quickie Check Engine scans they will suffice.

The cheap-o OBD2 scanner will not likely read voltages, etc. The easiest way is to find you multimeter but lacking that, how old is the battery? There may be a sticker on it, or one of the terminals may be stamped with the manufacture date. If it's 5 years or more, just replace it.

 

Hi Y2K,

Sorry about that, it's a 2001 XK8.

I located my OBD2 and plugged it in. No codes but the check engine light is still on.

Now with any luck I can find my multi-meter and see what the battery gives me.

I am not seeing any date on the battery. It's a Duralast from Autozone so I'm going to call them and see if they can tell me from the UPC when it was purchased.

By the way, I'm in Placentia. Nice to meet someone close.

Joe

 

The date on the battery is 02/24. I still haven't been able to test it yet, but since the car is running normally (al be it with the check engine light on) I'm going to drive it to the Autozone store and have them test it. Unfortunately their 2 year warranty is only good for the person who bought the battery.

Joe

 

I found my multi meter. The battery is putting out 14v. Check engine light is still on.

 

Well I finished putting everything away and got into the car to run to the store since the engine seemed to be running ok and poof, no messages AND no check engine light. I took it to the smog testing site and when the guy there put his OBD2 on it he got a fault "Air Mixture Solenoid Circuit Malfunction." I went over with him the steps I had taken and told him that I put my OBD2 on it and got no faults. He said he wasn't sure what this fault meant but that it could have something to do with my running the diagnostics. He said he couldn't run the smog test because my use of the OBD2 reset everything and the test would automatically fail. He told me to drive it for a while and come back.

Anyone know what that message means?

Joe

 

If you're seeing 14v then I assume you are testing with the engine running - or you have a faulty meter! 14v running shows good alternator output, but gives no information about the battery itself.

 

You're right Blade, the engine was running with the 14v reading. Engine off it's 12.5v. Thought I had that in there, but apparently not.

Looks like this other issue has to do with connectors at the throttle body. I'll see if I can pull all the plastic parts off and check them out tonight.

Joe

 

I think the 1251 has to do with the Throttle Motor. That connector is on the RH side of the throttle body. It's the cylindrical connection. The 4-pin connector below it is the Throttle Position Sensor connection. In the fusebox on the RH side under the hood, fuse 9 is the appropriate fuse. There's also a relay but I don't know where that is offhand. Probably in the same fuse block.

And yes, after clearing any code the OBD monitors are also cleared, as Gavin said, "whether you like it or not." So, you have to put on maybe 100 miles, definitely some of those should be on the freeway, before they'll all set.

 

Interesting that there's a light but no codes on your scanner. Maybe another scanner is in order. I have a cheapie Actron (no longer made) that reads the OBD monitors and all the engine codes. If it doesn't know some, like the 1251, it will just say Refer to Manufacturer. It certainly can't read other modules, but for quickie engine stuff it's decent.

There are several threads concerning good scanners to buy.

 

On the way to the store as I drove away all the lights came on again, same messages. I opened the trunk/boot just for jollies and checked the battery connections. Duh!! I don't know who installed the new battery but the ground cable was very loose, like move it with my finger. I tightened it up and all the messages and lights went away. I'm still not sure about that last message, the Air Mixture one, but I'm going to get a better OBD2 and see what I can see.

I checked out several of the threads with recommendations for better OBD2s but all the links I'm finding are no longer good. I'll just keep searching.

Joe

 

Went out last night and everything was fine. Went to start it up this morning and nothing happened the first 3 times I turned the key. Fourth try and all the same messages and check engine light came on. After shutting it off and restarting 2 more times, the messages went away but the check engine light is on. I ran my quick errand and got the same nothing the first few times I turned the key, then it started and just the check engine light is on. I'm going to throw my OBD2 on it and see if there are any codes.

 

I’m wondering if there’s something draining the battery and causing all the problems? Once the car is started and I drive for several miles when I start it next time everything is fine. It seems to happen in the morning after it’s been sitting overnight but then, after a drive, it all starts normally. Anyone else have a problem like that?

 

Info for you.

 

Thank you Bob. With any luck I'll figure this matter out, but it is frustrating.

Joe

 

The P1251 is a clue, probably.

But... if your OBD tool doesn't report it I think it's got a serious bug so I'd get a different one maybe an elm327. Very cheap. Good with such as the Torque app.

 

Hi John,

what software do you use with your ELM327. I’m going to order one today and I have an Apple iPad that I can use with it. I’ve been reading reviews and so far it sounds like the TOAD software is ranked as the best option. I’m seeing it for under $100.

Joe

 

So I get in the car today, after it's been sitting for a few days in the garage, and it starts right up. No messages, no check engine light, nada. Maybe the bug is gone. I'm waiting for my new ELM327 wifi unit to show up tomorrow and run the Torque Pro app on the phone and see what happens.

Joe