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Vans & Minivans Mazda MPV Mazda MPV: Error Codes/TSBs/Recalls
65 messages, Last post on Sep 03, 2009 at 8:08 PM
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Replying to: whyland (Feb 20, 2008 5:27 pm) However, it is often difficult to diagnose ck eng lite problems from just the codes. The codes do tell you what parts might be involved, but not to what degree, or in what order, or whether a partial fault in another sensor is cascading to the code in question. With O sensors age causes a decline in performance. Thus you may get an intermittent code that does not always appear immediately. Note: The two sensors in front of the cats (catalytic converters) are the most important sensors used by the computer for determining fuel mixture. By tracking and responding to these two sensors the computer determines power, fuel mileage, rich/lean conditions which affect the life of the engine and the life of the cats. The second two O sensors tell the computer how well the cats are working. They determine whether or not you will pass an emissions inspection. Information from these sensors can tell you if your cats are bad. Of course the sensors have to be in good working condition. Just reading codes will always leave you guessing at what to replace. Even excellent mechanics can only guess at the problem with just a code. Four months ago I invested in a new code reader. I bought an Actron Elite Autoscanner Pro CP9190. You can buy them online for about $300. Now I know that seems like a lot of money but with the cost of repairs these days it will save you thousands. What is cool and better about this scanner? This scanner gives you realtime readings of the sensor outputs that are coming back to the vehicle's computer. I am diagnosing my MPV today because it's time for inspection again. Last year I barely passed by clearing the codes then driving the veh about 400 miles until the monitors all registered ready. I got away with that because the veh would run about 700 miles before throwing the OS2 code. This year will be different. Of course last year I did NOT have my new reader (CP9190). So what does the new scanner tell me that the original one can't? I can now watch a real time graph of the output from any sensor on the car. I can now see that my O2S22 (that's bank 2 second sensor) has a very erratic output. It only operates from about .3v to .7v. Further it's response time is highly degraded. The O2S21 is in great shape running from .1 to 1.1v with a fast response time. Both of my bank one sensors are working well enough not to trigger a code but the are running from .2v to about .8v and they respond slowly to changes in the fuel conditions of the engine. They are close to the end of their life span. That means my engine is running a bit rich, wasting gas, polluting the air, losing power, clogging my cats. If I replace them now (about $100 each) I can save replacing my cats for $2000. Otherwise running too rich will ruin the cats much quicker. Further, because they are near the lower end of acceptable they could also begin to throw intermittant codes as the weather temperurature changes. (other variables will also effect their performance). Why weather changes? Because temperature, air density, and moisture levels affect air/fuel mixtures and their related sensors. There is a huge advantage to having a scanner which will give you real time readings and graphs of the sensors. Even without any background you can spend a little time comparing sensors and figure out which sensors are under performing. Further you can do live experiments which help in diagnostic. For instance my O2S 22 is under performing badly. with the engine running and the scanner going I unplugged the sensor coupler. The engine continued to run just fine but the scanner voltages went to zero. I plugged it back in and wiggled the coupler to verify contact. With this little test I am more certain the sensor is bad and the wiring is ok. Another trick you could do with the same set up is pull a vaccum hose off and watch the sensor go low, showing that the fuel mixture is too low. This kind of simple experimentation could help you rule out air leaks. Rev the engine up and down, if the sensor shows good range .1 to .9 and quick response the sensor and the wiring are fine. If is show lean conditions during idle you likely have an air leak. In a nutshell. Simple code reading will totally leave you guessing, often lead you down the wrong path, and likely end up costing you far more money than it should have cost. For that matter, ANY mechanic that is making suggestions or diagnosis without a real time scanner cannot be giving you your money's worth. Find a friend or mechanic with a graphing scanner.
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Replying to: kprime2 (Feb 23, 2008 8:46 am)
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Replying to: whyland (Feb 23, 2008 9:39 am) My 2001 MPV has 129K miles on it. I am also getting error code (P0428) This code basically means the cats are under performing. If I gave this code to a mechanic he would likely suggest the cats need replaced. They do not. It's a bogus code. This code is derived by the computers comparison of OS2 #1 relative to OS2 #2. However since I can see that OS2 #2 is operating well enough to turn the ck eng lite only occassionally, but definitely operating very poorly I know the P0428 code is a false code. The computer makes the comparison and determines the cats are bad. The computer does not do a reasoned analysis and give me a print out that say's "Hey dude, your second sensor in bank 2 is almost out of spec and therefore it looks like your cats are going bad. You need to replace that sensor so I can get a good reading". It just throws codes after a couple hundred miles. The sensor is not in complete failure, therefore I when I reset the codes the light does not come right back on. If you study how the computer works with the emissions portion of its job you will find out that after re-setting the codes all cars have to be driven through a number of test variables over several hundred miles before the computer will give it's opinion. That's why you read a lot of cases where a part is replaced and then a week or month later the light comes back on. It takes the computer that long to do a full running analysis of the engine performance. If you live in an area where they require emission testing you cannot just reset the codes and pass the test. After you reset the codes the code readers will report that your sensors are NOT ready. Not ready means the car hasn't been driven far enough for the computer to make it's analysis. After re-setting you then have to drive it for about 2 weeks, several hundred miles, before it will pass inspection. You can also find, on the internet, the exact driving conditions the computer is looking for and purposely go out and create those driving conditions. When you follow the plan your computer reports the sensors or conditions are ready. Once the computer is in the ready state, if there are no current or pending codes, you will pass inspection. You ck eng lite will not be on. However, if one of the sensors is performing poorly sooner or later the light is going to come back on. Today's engines are designed with fail safes. That is why there are so many cars driving around with ck eng lites on. When a sensor is bad the computer defaults to a known workable condition and the engine continues to run without any fine tuning by the computer. They do this so you won't get stuck on the side of the road with a dead engine. However, this condition produces poor gas mileage, less power, more pollution, and runs the engine too rich. That will lead to early failure of the cats. In my case for instance. I could have a mechanic replace O2S 22 and reset the light. Say I pay him $400. Then after 400-600 miles the light might come back on. Let say for instance if the computer feels that bank one in not performing within spec on just one bad weather day. I go back and the mechanic scratches his head and says well guess we will have to replace another sensor, or maybe he will guess my cats are bad and tell me I have to replace the cats and the sensors but he's not sure. On the other hand maybe my MAP sensor, which measures atmospheric pressure and effects the computers decisions is under performing. This could cause the computer to think my cats are not doing a good job because the engine is running to rich. See the computer doesn't "think" in a car. It only reports. It does not know why certain conditions exist; it only knows that some signal fell below parameters. It take human analysis to pinpoint the problem and determine if its a single item or the result of a mix of variables. The mechanic cannot make this judgment, any better than the computer, without running the car for a few minutes and watching a live performance of the sensors. He may even have to take it out and drive it, with a scanner in live mode, in order to see where and when the problem occurs. My new scanner can record all the signals over a period of time. When you get done driving you can unhook it and review the stored data. You can hook it up to your computer through USB and print out the data and the graphs. It can also be set to start recording only when a DTC code (diagnostic trouble code, you know the thing that turns on the ck eng lite) is triggered. For $300. it's an awesome diagnostic tool. It doesn't take long to learn how to read most of the outputs. Things like intake air temperature, engine rpm, speed, timing, stuff like that you can assess just by watching the scanner. I have 5 vehicles I take care of; all for family members. I can run comparison scans and learn kinda what to look for on the scanner. You don't have to go to school to figure this stuff out. All of today's engines run pretty much the same way. You can make valid comparisons from one car to the next and generally tell if the sensors are reporting good data. Excellent article on O2 sensors. http://www.autotap.com/articles/Understanding_Oxygen_Sensors.html |
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Replying to: aa0526 (Jan 05, 2008 7:46 pm)  The mechanic (not dealer mechanic) initially thought we should replace the following: 1. Mass Air Flow Sensor 2. O2 sensor (before or after cat converter) But after removing each one and cleaning them --- it turns out - the sensors were just dirty! I only spent for the labor + a little for diagnostics. Car runs like new again (at 110K)!
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P0031 My turn for emissions inspection came up again. My analyser indicated that the heater for O2S 11 (bank one sensor 1) was faulty. It would not pass inspection. I ordered all 4 O2 Sensors from a dealer back east http://www.trademotion.com/, I believe this was the site. Paid $99 ea with low cost shipping. My MPV has 130K miles on it and the O2s are supposed to be changed at 100K so I figure just get them all done at once. Took it too a local mechanic (non-dealer) that has done some work for me in the past. He charge $120.00 to replace them all. CEL went out. I drove the van through the ready cycles and all lights were off. The emission managers were 'ready' so I drove it right over to the inspection station. It passed. Since your engine is over 100K don't be surprised if your O2 sensors start throwing codes again in the next year. I would order OEM parts and take them to your mechanic. Congrats on your current repair tho.
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I recently brought my 2003 MPV in since the Check Eng. light had come on for two days...then went off on it's own right before bringing it in. The dealer said that the code was to REPLACE THE CATALYTIC CONVERTER! $1000 job! I had never replaced one in 30 years of cars and I was quite upset. Have any of you heard of this issue with MPV's? I called another dealer to inquire and that person said not common, but it COULD happen. I have no other signs of problems...yet. Engine seems to be running fine and no 'loss of power' as is the telltale sign. Does this seem right? I have 99K miles on it and, of course, Mazda only covers this unit up to 80K miles! Is there any recourse? Also; had to have the fuel sending unit replaced due to gas gauge not reading correctly. THAT was under my extended warranty and would have been $200 cost. |
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My 120K 2002 MPV ---- is experiencing very rough idling at neutral at 600. Putting the van in Drive smooths out the rough idling but the idling is still pretty lower than usual around 800. The EGR valve was replaced under the recall at 70K about 3 years ago. Should it get replaced again? There are no CELs or codes showing up ... what could be wrong? |
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Replying to: aa0526 (Dec 01, 2008 3:50 pm)
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Replying to: aa0526 (Dec 01, 2008 3:50 pm) |
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Replying to: aa0526 (Dec 01, 2008 3:50 pm) I would still check for codes at a Autozone, or somewhere done free. My MPV was running rough with no CEL. When taken to Autozone the code showed up on the scanner as a faulty ignition coil.
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