QuestionHi Roland,
About a month ago I took my car to a shop because the water pump was broken. When the guy checked my car, he said that the timing belt needed to be changed because it was about to break. So I told him to go ahead and change it, but when he gave me the car, the very next day the check engine light came on. I took it back and he told me it was an oxigen sensor and that he didn't know how to fix it. I took my car to the Autozone and the code they gave me said that it was that the timing belt skept a tooth. But then I heard from someone that those kind of cars need to be re-learned after the timing belt is changed. Its that true? Do you have any idea whats wrong with my car? I took my car again to the guy that change the belt and he still insist isn't the belt, he claims is an oxigen sensor. What do you think?
Thanks,
Gloria
AnswerHi Gloria,
Thanks for the follow up telling me it is a P1390 code. I have to correct myself on two points: the code does mean the belt has skipped one or more teeth and there is in the case of that code the possibility that the engine controller has to be instructed to 'relearn' the relative position between the cam and crank sensors after the timing belt is changed.
That being said, a question I have however is whether this code was set because of the weak belt before the timing belt was removed or was it set afterwards? If it was set before then it is possible that it is just a stale code due to the worn out belt having skipped a tooth. If it was set after it could be due to either the belt not being installed properly such as to have the proper alignment between the crank- and the two cam shafts or it could indeed just be a need for the dealer to put a diagnostic readout box on the plug in the car under the dash and tell the engine controller to "relearn". If the mechanic didn't actually check the alignment (as I will describe below) when you brought it back to him I don't trust what he said.
So that is another reason for you to do the code erase by simply taking a wrench, loosening the nut on the cable attached to the - post of the battery, remove the clamp for 5 minutes, then hook it up again and tighten the nut. Then drive it for a day, see if the light comes on again, and if it does go back to Autozone and ask for another readout.
You will get a 1684 (battery was disconnected) but the question is do you still get the 1390, which if the light came on means it is probably back again (because the 1684 by itself won't turn on the light)? But then you will know the problem is still present.
But the question then is whether the belt was not aligned by the mechanic who changed it, or does the powertrain controller just need to relearn? There is a way to check the belt alignment yourself if you have the sockets (or a friend with sockets and knowhow) to turn the engine by hand until the timing mark for the top dead center of cyl #1 compression stroke comes into position on the crank pulley timing scale, then remove the plastic covers on the camshaft sprockets and see it their marks are lined up with the marks on the housing to which the covers were attached, or not. If not, then the mechanic goofed and needs to reset the timing (which he can do with much less effort than doing the whole job again, but it must be done, and he should not charge you for it; I can send him the instruction for doing it for your engine which I presume is the 2.5L V-6 (let me know if not) so he will get it right this time). Alternatively, you can go to a Chrysler dealer and ask them to check the timing belt alignment as I described above, or alternatively ask them to tell the powertrain to relearn the crank/cam relationship, and then see if the light and code goes away after driving it again (whichever costs less to do). If it doesn't then that would prove that the belt is not aligned without having to visually check it. But since you would already be at the dealer, asking them to visually verify the alignment might not be too much extra cost. Then if they found it to be 'off' then they wouldn't do the relearn at that time, but rather have you take the car back to the mechanic.
I know this is circuitous, but it is the only way I can see to get to the bottom of this question with the least cost to you. So try the code erase and maybe everything will be o.k. and the light will go away. Chances are it won't if it has persisted, but it won't cost you anything to start the process that way.
Roland
Hi Gloria,
Unfortunately you didn't tell me what engine and what year the car is. It may be easy to read the code yourself and then tell me what the number(s) are. But before you do that, disconnet the - post clamp of the battery for a few minutes to erase all the old codes, reconnect the cable clamp, then drive it until the check engine light comes on which will be an indication that the current problem has recurred and thus when you ask for the codes it will be up-to-date. Here is how:
Try using the ignition key: turn it "on-off-on-off-on" and leave it "on" (doing this quickly, no longer than 5 seconds). By "on" I mean just the normal position when the engine is running, not the cranking position. The 'check engine'light will remain on when you leave the key in the "on" position with the engine still not running. But then watch the 'check engine' light to begin flashing, then pause, flashing, pause, etc. Count the number of flashes before each pause and keep track of the numbers. Repeat the readout and verify the counts are correct. Then group them in pairs in the order that they came out, thus forming two digit numbers. You may notice that the pause is shorter between the digits of a given number, and longer between the numbers themselves. Then send me a 'follow-up' question telling me the results of your readout. By the way, 55 will be the last number (two groups of 5 flashes each) and that is the code for "end of readout".
I have the troubleshooting manual for several engines and we can look up the possibilities of what is wrong based upon what fault codes you show. There is also an essay on fault codes at the site:
http://www.allpar.com/fix/codes.html
which gives the meaning of the code numbers. But then you need to get specific info for what exactly might be the diagnostic tests or parts to replace to complete the repair. Let me know the codes and I can give you some direction.
I don't believe there is a code for jumping a tooth, and I am surprised that the mechanic says he can't change an oxygen sensor. But that is how it goes sometimes with repair people.
On the learning curve, yes that is true as regards the transmission, but not the engine controller. So we need to get the current code to see what it believes is wrong. If your car is too new to give you a readout, then go back to autozone, only this time ask them to tell you the exact numbers of the codes.
Roland
