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P0171 DTC code, Please Help


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First of all, I apologize to you for my limited English. I speak very little English.
I am from Guatemala and I have a 2004 Ford Focus Duratec 2.3 PZEV. Everything was working well, but several weeks ago the engine began to hesitate. Then it began to lose power to the point of shutting down the engine (Especially when uphill). I have an Innova 3030 scanner and when I connected it it showed me a P0171 error.
The report that shows me the software of the scanner is the one below this message. Can you help me interpret this report? Could you give me some clues as to why this code is being generated and if the values in the report are normal or are there any that are wrong?.
Here in Guatemala it is not so easy to find a service center that will fix these vehicles well since it is not a vehicle that would have been imported by the distributor. Please help me, I need to repair my car.
Thank you.

Parameter Description
DTC for which Freeze Frame was Stored
Fuel System 1 Status
Closed Loop
Fuel System 2 Status
Not Supported
Calculated LOAD Value
30.20 %
Engine Coolant Temp
190.40 °F
Short Term Fuel Trim - Bank 1
42.19 %
Long Term Fuel Trim - Bank 1
25.78 %
Intake Manifold Absolute Pressure
8.59 inHg
Engine RPM
1,274.50 rpm
Vehicle Speed Sensor
14.29 mph
Ignition Timing Advance #1 Cylinder
12.00 °
Intake Air Temperature
102.20 °F
Air Flow Rate Mass Air Flow Sensor
0.65 lb/min
Absolute Throttle Position
17.65 %
Commanded Secondary Air Status
Atmosphere / Off
Oxygen Sensor Output Voltage (B1-S1)
0.52 V
Short Term Fuel Trim (B1-S1)
42.19 %
Oxygen Sensor Output Voltage (B1-S2)
0.05 V
Short Term Fuel Trim (B1-S2)
99.22 %
Oxygen Sensor Output Voltage (B1-S3)
0.05 V
Short Term Fuel Trim (B1-S3)
99.22 %
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1 hour ago, Odlarhg said:

First of all, I apologize to you for my limited English. I speak very little English

I'd say your english is excellent.....!  Someone on the forum will be able to help I'm sure.......

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first i would check for any air leaks down side of the maf sensor its common for rubber pipes to split allowing extra air in, also you could try cleaning the maf sensor itself with the appropriate cleaner.

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On 10/07/2017 at 4:20 PM, Odlarhg said:

it showed me a P0171 error.

The engine is running too lean, meaning too much air, or not enough fuel, in the mixture. Or it could be the ECU just thinks there is too much air, due to a faulty sensor.

The fuel Trim values also indicate this. They should be near zero. 99% is way out! The ECU is compensating for the excess air by trying to increase the fuel above what it normally puts in.

First look for any air leaks into the inlet manifold. Vacuum hoses missing or damaged, loose joints, etc. A fault in the brake servo can give excess air, but will usually also cause braking problems, like hard brake pedal with poor braking.

Then look at the MAF (Airflow meter), assuming it has one. Most petrol engines have either a MAF or a MAP (Manifold Pressure sensor), sometimes both. These are used to calculate the mixture, so faults on either, or a dirty MAF, can cause this problem.

Next suspect is the O2 (oxygen or Lambda) sensors. Sensor B1-S1 is giving a very different reading to the other two. That may indicate a problem with that O2 sensor.

I guess B1-S1 is pre-cat, and B1-S2 & B1-S3 are post cat, but that really is just a guess. Maybe the exhaust splits in two just after the cat.

Normally, a post-cat O2 sensor will give a reading around 0.45v, and the pre-cat sensor should vary up to 0.8v and down to 0.2v. Post cat readings of 0v suggest the engine really is running lean, unless both those sensors have failed.

I hope you can translate this ok!

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