Motor Vehicle Maintenance & Repair [My car: 2004 Mazda 3] So, my wife came home from running some errands and told me the check-engine light was on and that the car was sputtering and felt like it was going to stall while stopped at stop lights. I went to check it out, maybe 5 minutes later, and I took it for a drive... everything seemed fine. The next day it happened to me. I got to where I was going and let it sit for 10 minutes. The car seemed fine on the drive back home. So, maybe letting it rest, fixes things? Later in the day I went out and it still seemed fine. I got to where I was going and let it sit for about 40 minutes or so. When I left, it was sputtering again. I drove 10 minutes then decided to try letting it sit a couple minutes in a parking lot.... so I went and parked, sat for a couple minutes and restarted, and it went back to normal for the rest of my drive - about 30 minutes. Later that day, I left work and it seemed fine for the first 30 minutes or so and then it started sputtering while driving again and really threatening to stall when stopped at the lights.

I tried the parking lot trick but it only worked for a couple minute then it went back to sputtering. Also, at stop lights when it's threatening to stall it smells kinda like rotten eggs. Sorry for the long story but I want to make sure I put down enough detail. Anyone have any idea what could be the problem?ozone air purifier cancer Here are the codes:total air sanitizer ozone P2178 - System too rich off idle bank 1air purifier help with haze P0335 - Crankshaft position sensor A circuit P2196 - O2 sensor signal stuck rich bank 1 sensor 1 I took it into the shop and they spent 5 hours troubleshooting the problem and eventually came to the conclusion that the O2 sensor needed replacing. (as Bob Cross suggested)

I got the car back and the next day the same problems started happening again and the check-engine light came back on throwing the following codes: P2188 - System too rich on idle bank 1 It's back in the shop now waiting on a solution. The car is now fixed - at least it seems to be. I've driven it a few days and the symptoms have not returned. The fix: the shop found that the MAF sensor was corroded, so they cleaned it up. engine mazda exhaust o2-sensor maf Checking a list of TSBs for this set of codes, this looks like a promising candidate: 01-028/04 MAZDA SPECIAL PROGRAM (MSP05) - 2004 MAZDA3 - O2 SENSOR DTC ERROR, P2195 / P2196 From what you describe, a problematic O2 sensor could easily lead to the idling, sputtering and smells that you describe. If the sensor is stuck reading full lean, it's highly likely that the car is pouring far more gas through the injectors than you'd ever want. Has the mileage dropped dramatically since the problem occured?

Did you find this question interesting? Sign up for our newsletter and get our top new questions delivered to your inbox (). I just had these exact symptoms with a 2002 Vauxhall Astra. As well as the Crankshaft Sensor error (and the garage confirmed it had previously thrown out an O2 sensor error). Mine was the EGR valve, with fuels that use a lot of additives (here in the UK that's 'supermarket fuel') the valve quickly becomes caked in carbon. The EGR (exhaust gas recirculation) recirculates gases back through the engine before leaving the exhaust in an attempt to lower carbon emissions. 9/10 you can just whip it off and clean it out with carb cleaner and it'll be good for good while longer. However, a lot of people, just take them off the car altogether. You'll often get (very slight) better throttle response in low revs and marginally better MPG (1-3). If you're engine is quite efficient anyway, removing the EGR will do more good than harm. In the case of my Astra, the ECU would need to be reflashed by the manufacturer to ignore the EGR not being in place (for me that's a P0400).

That said, replacing an EGR if it's easily accessible in the engine bay is a simple job that anyone can do. Take a look at prices online and consider going that route if carb cleaner does work and solves the problem in the meantime. I have a 2005 Hyundai Elantra, and I was getting OBDII error codes: P2626 Hyundai - HO2S Pumping Current Trim Circuit/Open Bank 1 Sensor 1and later, I also got P2196 Hyundai - HO2S Signal Stuck Rich Bank 1 Sensor 1 My car was sputtering, somewhat intermittently. It would intermittently lose power rather suddenly while accelerating. The egine was also cutting out while idling at stop signs/traffic lights. I found this thread, and I decided to clean the Mass Air Flow sensor first before replacing the O2 sensor. I used CRC Mass Air Flow Sensor Cleaner ($8), and sprayed it all over the exposed wires and plates inside the MAF sensor. It made a notable difference, and the sputtering/stalling seems to be gone. I cleared the OBDII error codes, and so far the O2 sensor codes above have not returned.

Since this was a 2 part fix, I'll add it as the accepted answer, though Bob Cross got half of it correct. I never checked the EGR as DeviateDefiant suggested as it was fixed before getting to it. The O2 sensor was replaced. The MAF sensor was corroded, so it was cleaned. I can't help but wonder if we fixed the MAF sensor first if the O2 sensor would've needed replacing. The codes were pointing to the O2 sensor though.... I guess we'll never know. Browse other questions tagged engine mazda exhaust o2-sensor maf or ask your own question.The mass airflow sensor (MAF) is located inside the engine compartment and is used to measure the amount and temperature of air that is entering the engine at any one time. Older-style meters used on fuel injection systems in the 1980s measured air volumetric flow, which worked fine, but then you also needed a separate sensor to figure out how cold or dense the air was. The mass airflow sensor senses the total amount of air passing the sensor and allows the fuel injection system to adjust the fuel mixture to compensate for cold weather and/or high altitude conditions.

The MAF also incorporates an internal intake air temperature sensor that measures the temperature of the intake air.The check engine lamp can be caused by a wide variety of problems with the engine--you need to read the codes from the computer to get a starting clue as to what the problem is (see Project 20 for details on reading the codes). It's perfectly safe to continue to drive the car while the CEL is on, as long as it is not flashing. It's best to get the problem taken care of relatively quickly, as running the engine in this condition can potentially cause damage to other components, such as the catalytic converters.The computer will know if something is wrong with the MAF because it will compare the values being output by the sensor to "expected" values that it should be receiving. This common sense check by the computer helps diagnose problems with every component in the system. If the MAF becomes dirty and is falsely indicating to the engine that the car is receiving very little air while at full throttle, then the computer will most likely kick back an error code.

To gain more information about the problem, you can try disconnecting the sensor completely and take the car for a drive. If you take short drives (30 minutes or less) with the sensor disconnected, it shouldn't cause any major damage to your car. The engine management system (DME) will enter into a type of "limp mode" that will compensate for the missing MAF. If engine performance improves dramatically when disconnecting the MAF, then the problem quite likely lies with the MAF.If the clamp on the throttle body happens to come loose and fall off, then the MAF will indicate almost no air being sucked through the intake, yet the engine will be sucking air directly from the engine compartment into the throttle body. The bottom line is that you should carefully inspect all of your hoses, clamps, and intake tubes for air leaks prior to replacing the sensor (see Pelican Technical Article: Finding Vacuum Leaks on the Porsche 911 Carrera).The MAF is located on the left side of the engine compartment, just behind the air filter (see Project 3 for access to the engine compartment).

For some reason, Porsche made it unusually difficult to remove the MAF by securing it with a T20 tamper-proof Torx screw. You need the special tamper-proof Torx drivers, which are not typically found in everyone's toolbox, but usually can be purchased at a good local auto parts store. Although the holes on the MAF look symmetrical, they are not, and the unit can only be installed in one direction. See Figure 1 for a close-up of the MAF. Removal is easy once you have the tool. Simply remove both screws holding it in place and pull it out.It's very important to keep the sensor clean. If the air cleaner isn't working too well, it could allow dust and debris to collect on the MAF. If you've had a problem with your air-oil separator, it could have contaminated the sensor as well. Oil sucked into the engine intake from a defective separator can easily find its way back to the intake tube. If you have had major engine problems (like our project car with the blown-up engine), then you may find a ruined MAF.

On our donor car, the MAF was soaked in oil and coolant residue that had found its way all over the engine. If you have an aftermarket reusable air filter, beware of how much cleaning and filtering oil you use on it. Excess oil may get sucked into the intake and find its way onto the MAF. To keep your MAF healthy, I recommend changing or cleaning your air filter often (see Pelican Technical Article: Replacing Your Porsche Carrera Air Filter (996/997)).If you are replacing your sensor, it is extremely important that you get the proper one for your car. There are two basic types, one for the cars that use a traditional throttle cable (1999 only) and one for cars with an E-gas electronic throttle (2000 and later). In addition, the later-style E-gas sensor has been updated at least twice as of this writing. Porsche updated the sensors in the Carrera in 2002 with the introduction of the 3.6 liter engine. Here is a chart that shows the differences between all of the sensors:1999 996 Carrera 2 (2 wheel drive)Sensor for use with cable throttle cars1999-2001 996 Carrera 4 (4 wheel drive)Original sensor for E-gas carsIn general, if the old sensor your removing has is a 123.00 or 124.00 sensor, then you should replace it with a sensor with the same part number.

If the old sensor you're removing ends in 125.01, then replace it with 986.606.125.01 (the latest version available).After reinstallation, reset your check engine light (CEL) using your code reader (see Pelican Technical Article: Reading Porsche 911 Carrera Fuel Injection Fault Codes). You can also disconnect the battery for a short while to reset the lamp, but I don't really recommend this approach (see Pelican Technical Article: Reading Porsche 911 Carrera Fuel Injection Fault Codes). On 1999-2002 Carreras, you can disconnect the battery for more than 20 seconds, but less than 50 seconds, to clear the trouble codes without having to enter your code back into your radio. On pre-2003 cars, the computer's CEL memory is cleared after being disconnected for 20 seconds, but the radio code is needed after 50 seconds disconnected.After you have replaced or cleaned the sensor and cleared the code, you need to go drive the car and see if the code returns. If the same error code appears, then the problem probably lies elsewhere.

Most of the time when you have an error code indicating a problem with the mass airflow sensor, it is usually solved by the installation of a new sensor. However, the computer can become confused sometimes and give misleading error messages. Wire harness issues, DME problems, and secondary air injection equipment problems may all give false MAF error codes. At this point, it's best to dive into the factory manuals and start going through the laborious test procedures contained in there. Shown here is the mass airflow sensor (MAF). The main sensor fits in a hole in the air intake right downstream of the air filter. The green O-ring seals the sensor to the intake tube (yellow arrow). If you're having trouble with your MAF, you can try to resurrect it by cleaning it. Lightly spray the areas shown with the blue arrow with electrical contact cleaner--the one that I recommend is CRC Mass Air Flow Sensor Cleaner. Spray it and then shake the sensor so that any dirt or debris is washed away.