Code P1141 for OBD-II

[nicebubby8]

My vehicle is a 1999 Mazda Protege with a 1.6L manual transmission. My vehicle is performing poorly and using a lot of gas. My trouble code is P1141 and the check engine light is on. Although I have looked at general OBD II codes, I do not have access to a list of Maxda codes. My best opinion is that this is due to the PCM entering open loop mode as a result of a faulty oxygen sensor, which would explain my symptoms. It's possible that the code I derived—H02S Bank 1 sensor 2 Heater Circuit Low Input—is incorrect for a Mazda. Is there any way to decipher this code? We're open to ideas at this point.

[Starcar2022]

True, what you say. When the back O2 sensor heater circuit is faulty, the code P1141 is thrown. The engine may enter closed loop and reduce emissions more quickly thanks to the heater, which helps warm up the sensors more quickly. However, the back O2 has no effect on the fuel/air ratio. Its only function is to help the engine computer track how well the pre-warm cat converter is doing its job. The PCM relies on the front O2 sensor to determine the exhaust mixture and make fuel adjustments appropriately. It's quite improbable that the code is to blame for the poor performance and gas mileage. Instead, check the mass air flow sensor located above the air filter. Has a terrible track record with the issues you're mentioning. Some people report success after cleaning these sensors, however I believe yours is protected by an extended guarantee for 7 years or 70,000 miles. Special Service Program #56 is where you may get your extended warranty.

[Rudy7831]

As a side note, with the introduction of OBDII in 1996, the vast majority of problem codes have universal meanings across car makes and models. That's why it's possible to use any generic scan tool: all diagnostic connections are in the same position and appear the same.

[nicebubby8]

Your help is much appreciated. I plan to investigate the possible issue with the mass airflow sensor and replace the rear oxygen sensor. You said that you had some success in de-gunking the MAS; could you explain your method? According to my repair guide, all 1999 and newer 1.6L DOHC engines have a single mas/iat sensor. It also specifies how to test both of them, or just one if you're using a combination sensor. Over the weekend (it is my girlfriends vehicle), I plan to do the diagnostic tests (my handbook specifies a voltage test for the MAS and an ohm check for the IAT). Do you know where I may find a reasonably priced components supplier if I am unable to clean the sensor? I called the listed number for Mazdaformance, but it was no longer in operation.

Once again, I appreciate it.

[nicebubby8]

And I almost forgot...For the purposes of the manufacturer's extended warranty, I have driven 134,000 miles on this vehicle.

[Rudy7831]

My mass air flow sensor (MAF) was clean when I removed it from the air box. The change was night and day after I washed the sensor's inside with brake cleaner that did not include chlorine. A helpful tip I picked up from the discussion here. The airflow meter, a small metal sliver, is very sensitive.

[Starcar2022]

To help you better understand the MAF you will be cleaning, I will send you a photo of one first thing in the morning.

[nicebubby8]

I really appreciate everyone's input. This is a fantastic forum, and you all are really kind to take the time to reply.

Regards

[Starcar2022]

The MAF in your vehicle is shown below for your perusal. To the best of my ability, I've indicated the locations of the IAT and MAF cables. Among them, the IAT stands out the most. This blurry closeup reveals the MAF cables embedded deep within the sensor. You can see them well with a flashlight. Two of these may be found below ground. The two you can't see are the ones who matter the most. Brake cleaner should be freely sprayed on both the wheels and the IAT. If you want a more targeted spray, use the little straw that comes with it. Examine the IAT from both the air filter side and the engine side when you initially remove the sensor. The side that isn't covered by an air cleaner will likely be a dull gray or black color. You need to make sure that all sides are polished and spotless.
Wait 5 minutes for the sensor to dry before replacing it. If you can't get the OE clean, expect to pay roughly $137. For aftermarket and remanufactured part costs, visit www.autoecms.com.

[nicebubby8]

Again, I appreciate it very much.

[migueldosantos77]

Can I clean the sensor without removing it? After having my technician replace the EGR valve and oxygen sensor to solve my malfunctioning check engine light, a new code (P1141) appeared in place of the old OE code. The technician also informed me that the air intake pipe on my vehicle was cracked. help needed, if possible.This automobile cost me exactly $500 right now. Plus, I have to have my car's emissions checked.

[TechnoTrailblazer]

My Protege 1.6L from 2001 experienced a similar issue. The car's engine has been acting up, particularly in heavy traffic, with poor performance and sudden shutoffs when completely warmed up. The check engine light finally turned on, so I took it to Autozone to get the codes. The codes were P1141 for the back O2 sensor and P0300 for cylinder misfires that seemed to happen at random. After reading this topic, I removed the mass air flow sensor and cleaned it with non-chlorinated brake cleaner as described above. I then cleaned the throttle body with its designated cleaner. The IAT sensor's tiny "bulb" was, in fact, quite grimy.

The check engine light turned off tonight, and the vehicle did feel better, but I won't know for sure that the issue has been solved until I've driven the car for a few weeks, since it only occurs seldom. If I don't provide an update here during the next two months, you may assume that a thorough cleaning of the MAF/IAT resolved the issue.