Check engine light

[cbriden]

Anybody ever had a check engine light that no one can seem to repair? This happened to me on a mazda 3 P2177 was the code. Never did figure it out. I paid the dealer to fix it and then gave up after two take backs. It sure was frustrating. I always wondered why obd2 doesn’t just tell you what sensor is causing the cel. The measurement is simply an out of spec voltage or current on a particular sensor. Why not just report the sensor and the out of spec measurement? instead I get “to lean off idle bank 1” which only makes sense to someone like scanner danner. Wish he worked in Florida, I would still be driving the mazda!

Topic

[Dustin Hicks]

A Mazda P2177 code is “system too lean off idle speed”. The car is telling you that accelerating from idle, the engine is either getting too much air or not enough fuel.

First question is: What year is the car?
Second question: Has the car been modified? (e.g. aftermarket cold air system, turbo, supercharger)
Third question: Are there other symptoms? (I’d expect stumble or hesitation on takeoff)

If you want to take a shot at it yourself, try this first:(just remember to check all hoses also)

[EricTheCarGuy]

People have the misconception that the CEL code is the be all end all. It’s not. As you pointed out the computer just sees voltage values, if it’s out of spec, it sets a code. It’s up to the technician to do the proper testing for that code to find the cause of the problem. Throwing parts at it is NOT diagnosis. Unfortunately this happens all too often. There are 2 main reasons for this, the first is that many technicians are ignorant of how to properly diagnose things. The second is that they are often not given the proper amount of time to do a thorough diagnosis because of the flat rate system. Lastly, many are just plain lazy and don’t want to put the time in. The take away from all this, if you find a competent technician treat them like gold because that’s exactly what they are.

[Jose Enrico Mallari]

[quote=”cbriden” post=55956]Anybody ever had a check engine light that no one can seem to repair? This happened to me on a mazda 3 P2177 was the code. Never did figure it out. I paid the dealer to fix it and then gave up after two take backs. It sure was frustrating. I always wondered why obd2 doesn’t just tell you what sensor is causing the cel. The measurement is simply an out of spec voltage or current on a particular sensor. Why not just report the sensor and the out of spec measurement? instead I get “to lean off idle bank 1” which only makes sense to someone like scanner danner. Wish he worked in Florida, I would still be driving the mazda![/quote]

A Scania truck came in with rough idling and engine stalling problems. Upon checking, found out the fuel pump was faulty. From what I experienced, It’s best to take sensor readings while the engine’s cold. Tested the speed sensor (it was part of the fuel pump so I had to take the back cover off ). Engine was hot so when I tested it, readings were still within spec. After a while I made another check and noticed the reading dropped. Then the next day I tested it again and this time, I could not get anymore readings from it.

[college man]

As suggested. check for vacuum leaks.Have you checked fuel pressure
or changed the fuel filter if it has one.

[Author]

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