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Discussion Starter · #1 ·
Hey everyone,

Just wanted to share my 'Lean Condition' P1273 drama.

So, I have 2004 Sentra 1.8S, CA edition (107K). No mods, all stock.

I just installed the 'Fuel Pump Repair kit' from courtesynissan to fix the 'Hard Start' issue. This problem has been solved since install of the repair kit. Soon after install, I got the P0128 - Engine Coolant Temperature defective. So I changed the sensor and reset the code, then problem solved.

After awhile, I got the P1273 code. This is for 'Lean Condition detected. Sensor 1, bank 1'.

Possible problem from FSM:
A/F Ratio (O2) sensor in Manifold,
Fuel injector/regulator
Leak in intake/exhaust.

My car did not have any leak and did not have any fuel issue. I found out that for my car, fuel pressure regulator is built-in to the pump assembly. This was replaced with the 'Fuel Pump Repair kit.' After many weeks with google and forum. No one really had a solid solution.

FSM has a section 'Clear the Self Learning Data' procedure. Apparently, anytime fuel component is replace, this procedure needs to be done.


1. Unplug MAF sensor
2. Start car for about 3 seconds. Turn off car. confirm P0102 code
3. re-connect MAF sensor. Clear code. START car.
4. Run car for 10 mins.

... no more P1273. (This should work for P1274 - Rich condition)

Hope this helps someone!

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