1998 Q45t service engine light

Post by **cjbyrd** » Tue Mar 11, 2003 2:35 pm

I just bought a 98 Q45t with 48,000 mi. I drove it 700 miles and the service engine light came on immediately after an oil change and gas fill up. The car runs fine. Is there a problem? How do I find out what the problem is and correct the problem? Is there a way to reset the light? Thanks.

Post by **greg_atlanta** » Tue Mar 11, 2003 2:35 pm

Is it still under warranty? Who changed the oil?

Time to visit dealer to have them plug the car into computer.

Also, make sure gas cap is secure.

Post by **vr4_for_fun** » Tue Mar 11, 2003 2:35 pm

I've got the same problem on my 98 q45t. I've just completed an oil change and now my service engine soon light is on. I had to disconnect a sensor and remove the plastic air guide that feeds air to the air filter to remove and replace the oil filiter. I've double checked that connection and it seems fine. The closest Infinity dealer is over an hour away. Anything else I can check/clean/reset to correct this problem?

thanks!Randy98 Q45T 'The Lowrider'

Post by **Q45tech** » Tue Mar 11, 2003 2:35 pm

If you guys are going to do it yourself [and change the oil filter improperly from the top] you better have a manual to make sure you reconnect things properly or a scan tool to read the problems you cause.

Is the air temperature sensor comnnected?

Post by **PalmerWMD** » Tue Mar 11, 2003 2:35 pm

What Q45tech said.Dont change the filter from the top you may get lucky the first or second time but eventually a connector is gonna get messed up.

Yes its more of a hassle to do it from the bottom but its the only proper way.

Recently we have been gettting a rash of calls for help, for check engine lights, or poor running after oil change.Always it turns out, owners changed from top.

Most common culprits: MAF Connectors.

As dennis often pointed out, they are not really made to be disconnected on a regular basis, but maybe just a couple of times in a cars lifetimeSummary: You may need a new MAF connector(dont let them sell u a complete MAF)

Fred...

Post by **autotech43** » Tue Mar 11, 2003 2:35 pm

Q-45 tech, your right on it!!! Seen that situation many times.

Post by **vr4_for_fun** » Tue Mar 11, 2003 2:35 pm

To change the oil from the top on my 98 q45t I only have to disconnect 1 connection (I assume it's the MAF), remove 2 screws and the plastic air intake tube. I can then reach down and remove the oil filter. There is even a drain underneath it so the oil in the fliter can drain down through a tube that exits under the car into a drip pan. It looks to me like it designed to be removed that way... Is it different in the earlier Q's? If this is the 'wrong' way. Can you please tell me the right way? Also, how can I reset the service engine light. The car seems to be running fine...

Thanks very much for your help!Randy98 Q45T

Post by **Q45tech** » Tue Mar 11, 2003 2:35 pm

The right way is to use a lift and pull the engine bottom cover so while the oil is draining [15 minutes] you can examine all the bottom parts for leaks, belts for wear, etc.

Use spray brake clean to clean off any grime, and any oil that dribbled where it shouldn't have.

The ODB2 MIL light can only be reset with a scanner tool.

Post by **Tgvince** » Tue Mar 11, 2003 2:35 pm

On my 97 Q ive forgotten to plug the air temp sensor back in and as a result thrown a MIL light. I disconnected the battery overnight. That cleared the light for me...Just an FYI.

TerryPS i change my oil the correct way:).

Post by **Falkdesigns** » Tue Mar 11, 2003 2:35 pm

Bringing up an old topic here.

I just got a 98 Q45t on Thrusday (3/18/04) and 3 days later the Service Engine Soon light came on. I looked a 3 cars and 2 of them had the light on when I saw them, but the one I got didn't. < (thats not why I bought this one) Any way, yesterday I took it into the garage I've used for years. I have full access here and worked there for a while myself so I usually go in on Saturdays and work on our cars.

I was checking fluids and it was high on the oil, which was very clean and new looking. I lifted the car up and drained off about a quart, just so it's a little below the top of the hash marks when warm. Everything else looked good, the car is clean as can be underneath, no oil, grime or dirt anywhere. Nice Cali car. The next day (today) the Service Engine Soon light carme on after driving around enjoying the new car. Any ideas from my description? I guess either way I have to take back to the garage and scan it huh?

Thanks for the help.

Post by **VA99Q45** » Tue Mar 11, 2003 2:35 pm

You can bring your car to AutoZone and they scan it for free. They can tell exactly what is the problem with your car.

My guess would be your O2 sensor causing it.

Post by **Q45tech** » Tue Mar 11, 2003 2:35 pm

Unlike the 90-95Q the 96 and later not only check sensors at start to make sure they are not open [0.0 volts return] or shorted [5.0 volts returned], but in actual running for an approximately normal reading [+- 10% or +- 20% depending on sensor].

The are also timers.........seconds since cranking to follow the coolant temp sensor.......it should get warm the longer the engine runs since starting till niormal. Same with induction air temp vs AC ambient air temp both should read nearly the same.

For emission purposed the codes are stored, even though discoing the battery may turn the light off........temporarily.

Every owner should purchase their own OBD2 scanner, they are cheap and useful for all 96-2006 cars at least. OBD 3 won't come out till 2008.

Post by **Falkdesigns** » Tue Mar 11, 2003 2:35 pm

Thanks for the replies. I will be scanning it at the garage this evening and I'll post the results of the scan.

One question about discoing the battery: does the stereo have a code I'll need to enter??

Also, from the carfax I can tell that for the past 2 years, this car only got 2000 miles put on it so it sat alot. I'll fill it up with premium today (91 for Cali) and put some Redline fuel system cleaner I have in there. I figure that will be good for it since it's sat so much. I'll be converting it to Amsoil when I do the oil in about a month, although whats in there looks brand new.

Post by **maxnix** » Tue Mar 11, 2003 2:35 pm

Might try a liter or two of ISO-HEET also, just in case there is condensation.

Post by **Falkdesigns** » Tue Mar 11, 2003 2:35 pm

Ok. We plugged in the scanner tonight and it says it's an O2 sensor (sigh of relief). So I'm gonna replace both of them. Thanks for all the tips. I filled up today with premium and poured the rest of the Redline Fuel System Cleaner in the tank (I work at Simpson Racing and we make the suits and crew apparel for Redline so we get free stuff). She runs perfectly and this stuff should help clear out a bit of the grime from only going 2k miles in 2 years.

Post by **suretytek** » Tue Mar 11, 2003 2:35 pm

If you've got a laptop that you can use with it, this is a pretty cool (and inexpensive) solution:

http://www.digimoto.com/

Jeff

Post by **Falkdesigns** » Tue Mar 11, 2003 2:35 pm

Thanks but unfortunatley for me I'm a graphic designer so I use Mac's. (actually it's not unfortunate since Mac OWNZ PC!) but for this type of stuff I'm always left out. Maybe I need to get a laptop for these situations.

After I got home, I thoroughly went over the service history and I see that in Dec. they replaced the TPS and an O2 sensor, so I guess I'll just replace the one that threw the code.

So far, I just love this car. What a dream to drive.

1998 Q45t service engine light

1998 Q45t service engine light

Same problem on my 98 Q45t

Am I missing something here?

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