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Old 20 Feb 2013, 10:47 am
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Default is the code P0172 "system too rich" bank 1 dangerous?

i have a 98 honda civic lx, the check engine light was on and it went off right after i put some gas on it at the gas station. i took it the the safety and emmisions place and the guy told me that wasnt a serious problem because it was off, it even passed that test. today in the morning my check engine light came on again and im guessing its because of this problem. What to do now? I dont have any more money right now because i just replace the ignition key and the distributor , a total of 500 dollars so it would be in the next two weeks to get something else fixed. can this wait? how much could it cost me? is it really serious?

Excuse my ignorance this is my very first car

thank you
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Old 20 Feb 2013, 11:01 am
Join Date: Aug 2007
Posts: 36

A P0172 code means that the bank 1 side of the engine is running too rich ...low oxygen levels or it has too much gas in the fuel/air mixture going into the combustion chamber or other related problems which upset the fuel/air mixture...and it could indicate a number of problems such as bad gas, fuel pressure too high, a bad MAP or MAF sensor, a leaking fuel injector, a bad O2 sensor, a vacuum leak, a cracked exhaust manifold on bank 1 side, etc..

It's not particularly dangerous to drive it that way for a short while but over time, it could lead to a plugged catalytic converter if it continues to run rich which can be expensive to repair. Best to have the car checked out by a good shop or mechanic as soon as possible to find out where the problem is. Does the car run rough at all? ...misfire? The shop that installed the distributor might want to recheck their work to make sure it is not related to that ...bad plug wires or a vacuum leak from something they did. You might also add some fuel injector cleaner to the gas tank...a product called Sea Foam works clean the injectors and other fuel system parts if that is what's causing the problem. Parts stores, small engine shops, outdoor equipment dealers, etc..carry Sea Foam.



You will more than likely not notice any drivability problems, although there may be symptoms such as a misfire.


A code P0172 may mean that one or more of the following has happened:

The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters can cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.

There could be a vacuum leak.

There could be a fuel pressure or delivery problem

Possible Solutions

Possible solutions include:

Inspect all vacuum and PCV hoses, replace if necessary

Clean the MAF sensor. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling

Inspect fuel lines for cracks, leaks, or pinches

Check the fuel pressure at the fuel rail

Check the fuel injectors, they may be dirty. Use fuel injector cleaner or get them professionally cleaned/replaced.

Check for an exhaust leak before the first oxygen sensor (this is unlikely to cause the problem, but it is possible)"

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