QuestionQUESTION: Hi Roland, I keep getting an engine code of 21 mostly when the car is cold. It comes on within 1 minute of starting the car and has happened the last 4 days straight. Then the car runs a little rough and feels like it is going to stall when I am at a red light. I brought the car to a garage and they said that they replaced the oxygen sensor but it didn't help. I brought the car back to them and they said that they tested the oxygen sensors and they were working normally. They suggested that carbon might be building up in the engine since it is an old car (The car only has 88,00 miles). I don't believe them and plan on taking the car to another garage. Other info: I did get a 51 code a couple of months ago and they replaced the oxygen sensor which solved the problem. I was getting a code 13 last week after they cleaned out the Throttle Body and the car kept stalling while idling. The garage noticed a broken hose and fixed it so that code hasn't come back. How many oxygen sensors does this car have? Could it be a map sensor problemor a wire? Any advice would be greatly appreciated. Thank you.
ANSWER: Hi RJ,
You didn't mention which engine is in the car, but in any case there is only one sensor on either of the three possible engines.
I would encourage you to disconnect the battery for a few minutes, which erases the codes (but will cause a temporary 12 code to be set, so ignore that) and then drive it a few times and re-read for current codes, repeating the process to sure you have an accurate count. Then let me know which ones are present.
A 13 is the MAP sensor, but let's be sure it is still comes back. And the wiring of the oxy sensors can be checked if you will tell me which engine. It is suspicious that you have replaced the sensor twice and it still may show a code, suggesting it is a wiring issue not a sensor issue.
You will need a volt-ohm meter to do that yourself.
Another possibility for rough idle is that the egr valve is sticking slightly ajar. It can be improved/corrected often by lubricating the stem of the valve which is accessible between the vacuum-operated top of the valve and the body of the valve, hidden inside the flange between those two parts. Use WD-40 on the stem where it enters the body and move it back and forth by means of the tip of a screwdriver inserted in the slot of the stem. If you don't know where the egr is tell me which engine you have.
Roland
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QUESTION: Hi again, it has a 4 cylinder engine. I think it is a 2.2 liter if I remember correctly but I could be wrong. I was told that it was a Mitsubishi engine by the person I bought it from but I don't know if it that is true. How do I tell which engine I have? Where exactly is the oxygen sensor and the egr valve? I do have a volt-ohm meter but I have never worked on a car before. By the way, they fixed the hose last Friday and I drove the car around for awhile on Friday and Saturday (I drove over 100 miles) and the Check Engine light never came on. It then came on the last 4 days in a row right after I started it. I have read your past responses and you said that the O2 sensor doesn't really kick-in until you drive the care for a while. Does this mean it is likely the egr valve or something else? What about the map sensor? I will try your suggestions and thanks again for your help.
ANSWER: Hi RJ,
I believe it would be the 2.5L 4 cyl which is the same block as the 2.2 so that is not an issue. It is not the Mitsubishi as that is the 3.0L 6 cyl. For either size 4 cyl engine you will find the egr to be located behind the engine, close to the front part(passenger side, next to the firewall). It is mounted vertically and is as I described it. Look between the round top which has a vacuum hose and the body of the valve which is bolted into a pipe where there is an open flanged area inside of which is the valve stem. Check/lubricate as described earlier.
I can't tell you which other part is possibly wrong until you do the code readout, and also of course check that egr to make sure the spring-action movement of the stem moves it downward to a dead stop so as to assure it isn't sticking ajar. That sticking will otherwise cause a rough idle.
The MAP sensor is a 13 code, so that is probably not the cause although it is possible for the MAP to be inaccurage and still not set a code. That could only be detected with a higher quality OBD-I reader such as the Chrysler DRB II. I await the results of your code re-read and egr check out.
The oxygen sensor's wires at the nearby plug: dark green/black trace goes to the fuel pump (the in-board most relay on the left strut tower), black/dark green trace goes to pin 41 of the engine computer's 60-way plug (on the left inner fender), black/tan goes to pins 11 and 12 of the same computer plug, and black light/light blue goes to pin 4 of the computer plug. So check continuity between the plug on the harness and those pins. Also check the 4 wires at the tip of the sensor proper as they are quite fragile and one or more could be damaged by the mechanics.
Roland
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QUESTION: Hi again Roland, I disconnected the battery and drove several times and then got the codes again by turning the key on and off 3 times. I got a 12-21-55. So once again I got a 21. I can't find the egr. I have any idea what it looks like since I saw pictures of it on the internet. Is it under the air cleaner unit (if that is what it is called)? If it is, how do I remove the air cleaner (it looks like there are 3 big round black screws/plugs that have to be removed with some type of square screwdriver. Does the egr have to be removed to check/lubricate it? Do I have to remove the O2 sensor to test the tip of it and also the continuity between the plug and the pins on the computer (I hop my terminology is correct)? Once again the Engine Light comes on each time within 1 minute of starting the car and it does it only when it is cold. Then it feels like it is going to stall (the idle gets very low) and is a little shaky at red lights. Today I turned on the A/C which sped up the engine and the car didn't feel like it was going to install. Thanks again for your help.
AnswerThe egr is under the bottom side of the air cleaner housing between the engine and the fire wall. You don't have to remove the air cleaner to get to it. Just use a shop light to look behind the engine near the front end of the engine. It is basically vertical, with a vacuum hose attached to the round top, a bottom part attached to a small pipe, and the flange/stem area in between. All you need to do is find the valve stem, spray some WD-40 on it where it enters the body of the valve, and move the stem back and forth via the slot in the stem with the tip of a screwdriver. You don't have to remove it.
On the O2 sensor, just inspect gently the wires where they enter the porcelain to of the sensor, but then follow the wires to the near by disconnect plug. Check the wires from that plug back to the engine controller plug on the left side wall. It either has to be some problem with one of those 4 wire, damage to a wire between the other side of the disconnect and the tip of the sensor, or possibly a contaminated sensor inside the exhaust manifol (for example is some of the anti-seize grease used on the threads contaminated the sensor itself). You don't have to remove to ispect the wires and to check the wires from the plug to the computer. I would not remove it until I had verified that the wiring is good. Then I would consider going back to last shop that replaced the sensor and ask them if the sensor may not have failed or been contaminated when they put it in.
Roland
