OK car buffs...what would cause my check engine light to come on after replacing a water pump?

Question

I've got a 1997 Jeep Grand Cherokee Laredo TSI and last week it started overheating and leaking coolant. Turns out it was the water pump, so I had that replaced. The mechanic who replaced it is a relative of mine, so he just fixed it in my driveway without the aid of any computerized testers or anything (and without charging me $300 dollars for labor!!!). What are the possible reasons for the check engine light to come on after this and should I be driving it around? Thanks!!!

Answer 1

He may have had to unplug a sensor when he replaced the pump, and he forgot to plug it back in.

Answer 2

Check that the sensor is A) plugged in and B) not bad.

Also, when replacing the water pump on a car that is overheating, it is always advisable to replace the thermostat. Your thermostat may be the problem.

Answer 3

Check engine light can come on for many different reasons. Last month I had 4 different things fail literally 1 day after another. So I would like to blame the first mechanic, I know enough about these parts and how they failed that they were really strange coincident.

So it may be to tempting to think your family guy did something wrong, it is best to get the check engine light scanned and stop guessing. Guessing is only going to cost you $$$.

As posted above, if you take it to AutoZone they'll scan it for free. But the scanner can be had for as little as $50 at AutoZone or Sears (if you can catch a sales). Also certain engine code requires one of these devices to CLEAR the condition (after repair). It is really good stuff to have (given you can use it for all the cars in the family).
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Poster below says to try and disconnect the battery. That's an old PRE-ODBII (pre 1996) car trick that doesn't work on ODBII (post 1996) cars.

http://www.samarins.com/diagnose/checkengine.html
http://www.troublecodes.net/articles/myth-conception.shtml
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Answer 4

You could have it scanned by autozone to see what the problem is. Before you do that look underneath the hood to see if maybe your relative forgot to plug a sensor in. Some times you might have to disconnect a sensor because it is in the way of taking something off.

Answer 5

It could be anything from a software issue to something more serious. I know the agents are expensive but they have the proper software to diagnose and fix the problem. Take it to the nearest dealer and just ask them to plug it into the diagnostics and tell you whats wrong. then once youre armed with that info then you can get it fixed at a cheaper place - maybe even use your mechanic that replaced your water pump..... good luck!

Answer 6

There is no correlation between the water pump and check engine light. It could be coincidence or a vacuum line or electrical connection was disconnected or damaged during the repair. Check engine usually is caused by an emissions component.

Answer 7

Easy solution first. Disconnect your battery for a couple of minutes to reset the vehicles computer. Sometimes those lights are flukes. Once you reconnect, crank up and check the light. If it's still on you've probably got a wire loose somewhere.....

Answer 8

it has a mind of its own ,and thinks you have money to spend on it .
or some one did not plug somthing back in.
get your self a tester for reading the codes. just like paying your relative.except you'll want to keep the scanner.

Answer 9

in my town advance,autozone and o'reilly all scan for free.