Check engine light comes on - Toyota Nation Forum : Toyota Car and Truck Forums

bastholm · 09-29-2009, 07:17 AM

Hi and greetings from Sweden.

Thanks for this community. Always nice to have somewhere to go for free when you are in desperate need of some help. If something is lost in translation, please ask me to repeat myself :-) It's pretty hard trying to translate all the Swedish words to the correct English translation.

Well... I have a problem with my Toyota Corolla, 1.6 from 1993 with the 4A-FE engine.
I started with my radiator breaking. I ran the engine for some time without any coolant fluid (without my knowledge) and it got so hot that both the check engine and oil light lit up. I stopped the car instantly and towed it home. The guy at the Toyota dealer did a quick check filling up the radiator with water and looking for water sipping out from the engine, but he couldn't see any.
When cool again, I checked for white stuff in the engine (water) - none found.
I replaced the radiator, thermostat, oil, oil filter and the sensor controlling the fan (as the fan wasn't starting even if the car was hot, but it could be started as soon as I disconnected the cable to the sensor).

Now the check engine light comes on when the car gets a little bit hot.
I have two indicators (as the rest of you with the same car) on the dash board - economy and not economy. Green and orange. As soon as I give "too" much gas, and the light hits orange instead of green, the check engine light comes on.

I ran the diagnostics and got the code 52, which means KNK Open or short circuit in Knock Sensor.

As I have understood reading these forums, the knock sensor rarely breaks.
I can't even find it so that I can reseat it and its cables.
Do you guys have a clue what could be wrong? Or do you think I should start with trying to find a cheap one from eBay and replace it?
Here in Sweden, I can only buy it new (from my Toyota dealer) for about $200, which is a bit too much I think.
Could someone maybe take a picture of it and its location so that I can take a look at the cables?

I almost forgot; I also replaced the spark plugs.
And, the car seems a bit more uneven in the way it responds to received gas. It feels slower than before. When I press the accelerator (the gas pedal?) it doesn't respond as "quick" as before and seems as it's sometime struggling.

Thanks in advance guys! And, if you think that I was unclear on any point, please let me know :-)

Kind regards,
Martin

kevmac · 09-29-2009, 11:07 AM

Does your temp gauge lever stay level (horizontal) at normal op temp? How about the plug wires? Check resistance and/ or replace if old. cap, rotor as well. You may have yanked the wire on a plug causing a bad cylinder.

bastholm · 09-29-2009, 11:46 AM

Quote:

Originally Posted by kevmac

Does your temp gauge lever stay level (horizontal) at normal op temp? How about the plug wires? Check resistance and/ or replace if old. cap, rotor as well. You may have yanked the wire on a plug causing a bad cylinder.

The temp level lever stays horizontal. Never goes above the middle mark.
If you by plug wires mean the wires connected to the spark plugs, they all seem OK, but I'm not an expert. First time I touched those wires were weeks after the light started coming on and the car behaved a bit strange. When removing those wires to change spark plugs, I was very careful. I only pulled in the rubber thing shaped like a square. When you say "cap, rotor", what do you mean by that?

Thanks for you answer,
Martin

iToaster · 09-29-2009, 01:03 PM

By cap and rotor he means those parts on the distributor (the thing the spark plug wires come from). The cap is what they connect to and the rotor is the piece that spins around behind the cap that's responsible for sending the electricity to a specific wire to get the spark plug to make a spark. It's odd that you'd get a knock sensor code, especially considering the 4AFE doesn't have a knock sensor.

bastholm · 09-29-2009, 01:22 PM

Thanks for the answer iToaster. Quite odd that you say that the 4AFE doesn't have a knock sensor. I found one on eBay Motor which is for the 4AFE and when I called the local Toyota dealer, they should have told me that that engine type doesn't use a knock sensor. Are you sure about that?

iToaster · 09-29-2009, 02:19 PM

I have yet to see a 4AFE with a knock sensor, as well as all of the articles I've read online saying that it doesn't, and it also fits with you being unable to find it. Of course, there could be some country specific requirement that might have lead to the Swedish 4AFE getting one, but I don't believe this is the case.

bastholm · 09-29-2009, 02:27 PM

Here is the eBay item with a knock sensor for the 4AFE.

http://cgi.ebay.com/ebaymotors/93-94...ht_2280wt_1163

If you scroll down, you also see that it's valid for these model;
1993 / 1994 / 1995 / 1996 / 1997 Toyota Corolla 1.6L or 1.8L (Engine Code: 4AFE or 7AFE)

I went out and tried to compare any of the sensors with the one in the picture on eBay, and I actually think that I found it in the bottom of my engine, to the right.

But, let's say that my Corolla has a knock sensor and the code, 52, is "valid" - should I replace the knock sensor or is it more likely to be something else?

Thanks again for you replies, they have been helpful.

kevmac · 09-29-2009, 02:55 PM

get 4 new ngk plug wires and ngk plugs (not cheap wires or american/ german plugs). get a new cap and rotor (any auto parts). Chances are they are very old and possibly the original parts that have gone bad. These parts all wear out.

iToaster · 09-29-2009, 03:17 PM

The knock sensor would be found just below the center of the head of the engine in the block if you had one. Assuming the code is valid, it's more likely to be an issue with the ignition system or even the computer. I'd say you should go for a tune up and replace the spark plugs, spark plug wires, distributor cap and rotor.

1jzdreamer · 09-29-2009, 03:53 PM

I have this code come up intermittently on my gf's 7afe. I am going to swap out the knock sensor as if a mechanic or someone hit it, it could fail. Also a bad ground is enough to cause issues with it.

hungt1999 · 09-29-2009, 03:53 PM

Bastholm

go to the following site and enter your vehicle serial number (VIN) and see if your car is equipped with a knock sensor

http://www.toyodiy.com/parts/q.html

it is useful also to get parts numbers etc.

bastholm · 09-29-2009, 05:08 PM

Thanks a lot guys. According to the site you gave me, I found out that my Toyota actually have a knock sensor (engine 4A-FE). Link; http://www.toyodiy.com/parts/p_E_199....html?hl=89615

I replaced the spark plugs yesterday. I had NGK plugs and I inserted new NGK plugs.
So, my problem with check engine light could be solved with a new cap and rotor?
The wires seems a bit overkill. They cost a bit too much just to change them without knowing if they would make a difference or not.

I think I will start with locating the knock sensor (and what I can make out of it from looking at the picture, it's on the back of the engine), check the cables to it. If they seem OK, I will buy a new one through eBay. I will also buy a new cap and rotor.
Could it be something else?

Thanks again and thanks to hungt1999 for the excellent site with parts.

edit:
Question; Why will the check engine light first come on after a while if cold and instantly when warm (if I give a bit too much gas)?

iToaster · 09-29-2009, 10:00 PM

Here's a picture of where you should find it. It's directly under where the intake manifold meets the head between two freeze plugs on the block. It's a tight fit to even get a picture of so I be it will be a pain to try and check out.

bastholm · 10-01-2009, 01:33 AM

Thanks for the picture iToaster. I haven't had the time to check very extensively, I just popped the hood and looked down. I think I located it, but I'm not really sure.
When I have the engine in front of me, with the oil filter on my left side, I look down to my right. In the bottom there, I think I can see the knock sensor, but I'm not really sure. When looking at the picture from the site hungt1999 gave me, it seems like it should be on the back of the engine.

Maybe I could try taking some pictures (if it could stop raining..) of different sensors and let you guys have your opinion about it?

Thanks again.

iToaster · 10-01-2009, 01:50 AM

I'm thinking that you found the oil pressure sensor. The knock sensor is going to be on the rear of the engine just under where the cylinder head meets the engine block between cylinders 2 and 3, seeing as it works best when put there. Like I said, it's a pain to get at, especially to try and see, but if you have one it'll be there.