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Randall C
Randall C, ASE Certified Technician
Category: Car
Satisfied Customers: 12803
Experience:  32 years Foreign / Domestic Cars All aspects of Diag and Repair
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Mazda3, Im getting a code P2187 system too lean at idle bank1 .

Customer Question

Mazda3, I'm getting a code P2187 "system too lean at idle bank1". What could it be?
Submitted: 7 years ago.
Category: Car
Expert:  Randall C replied 7 years ago.
hello, how does the engine run/ any missing or other symtom at idle OR while on the raod? How has gas mileage been?
Customer: replied 7 years ago.

I noticed the following symptoms:

1. every time I fill it up with gas, it does not want to start up by itself. I have to help her with the acceleration pedal. But it does this ONLY the 1st time I start it up after gas refill. The subsequent times she is fine.


2. when runs idle (waiting at a red light for example), you can see that it almost chokes (it starts vibrating slightly). In the past, it happened once that I was stopped at a STOP sign, wanted to go after a full stop, and it stalled completely.


Hope this helps.

Expert:  Randall C replied 7 years ago.
Thanks, XXXXX XXXXX will see the diag chart we are confronted with. the problem could be one of several in the list. We can narrow out some like bad o2 sensor, exhaust leaks, fuel leaks etc but I am now thinking of narrow down to possible early fuel pump failure signs. Fuel is stored in tanks undergraound and is ice cold when you pumpit. the fuel pump runs at very high speed and hot and the gas cools it. When you shut off car at the pump, the fuel pump actually increases in temp, hit it with ice cold gas from the fuel pump, and they can react by not pumping or pumping slow. Most fuel pump failures happen at a gas station. the miss at idle, lean fuel condition and then the stall out, leads to the pump but... a fuel pressure test under different conditions will have to confirm this. O2 sensors normally do not cause a running problem, just light and maybe bad gas mileage. Not a fuel filter as the problem would be constant. I am going to say weak fuel pump. cant be 100% as this is by elimination primarily and not looking at scan data. I hope at least you knwo what the worst case scenario would be.

Customer: replied 7 years ago.
So, in a priority order, 1-2-3, what would you check first ?
Customer: replied 7 years ago.
I had some other 3 codes on it, (P0340 camshaft position sensor, P0455 evaporative emmision control..., P0661 intake manifold tuning), but they dissapeared once the mechanics fixed it. Now I'm left just with this one, P2187.
Expert:  Randall C replied 7 years ago.
I have given all info I can per code 2187. the prior codes etc now complicate things. I need to opt out and let another expert help you. Sorry I could not
Customer: replied 7 years ago.
Thank you Tracer, for your time. Anybody else, other ideas ?