P0171 code what is wrong?

ROYALSTAR

MEMBER
2004 CHEVROLET SILVERADO
120,000 MILES

I am receiving a P0131, P0300, and a P0171. I replaced the Bank 1 Sensor 1 O2 sensor on 6/21/2013. I cleared all codes but by the next day the MIL was on and the same codes are back. I have also replaced the MAF sensor and put a bottle of GM fuel treatment through my system on two different tanks of gas. I am out of ideas and I was wondering if I would receive these codes for bad intake manifold gaskets? Or are there other reasons for these codes? I appreciate the help.

1 Reply

ASEMASTER6371

MECHANIC
52,797 POSTS

Ok, 171 is a lean code. most likely a vacuum leak. it will be one bank 1 which is drivers side. This guide can help us fix it

https://www.2carpros.com/articles/repair-lean-mixture-codes-p0171-or-p0174-on-some-manufacturers

131 is a heater code for the bank 2 sensor. below is the flow chart for the code.

since you provided no engine size i am generalizing on this. it would help if we had the long term trims for both banks.

Roy

DTC P0131

CIRCUIT DESCRIPTION
Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature. The powertrain control module (PCM) supplies the HO2S with a reference, or bias, voltage of about 450 mV . When the engine is first started the PCM operates in Open Loop, ignoring the HO2S voltage signal. Once the HO2S reaches operating temperature and Closed Loop is achieved, the HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage. High HO2S voltage indicates a rich exhaust stream; low HO2S voltage indicates a lean exhaust stream. If the PCM detects an HO2S voltage that stays below a specified value, DTCs P0131 sets for HO2S bank 1 sensor 1, or DTC P0151 sets for HO2S bank 2 sensor 1.

CONDITIONS FOR RUNNING THE DTC

Lean Test Enable:
DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0169, P0178, P0179, P0200, P0220, P0300, P0442, P0446, P0452, P0453, P0455, P0496, P1125, P1258, P1516, P2101, P2108, P2135, U0107 are not set.
The Loop Status parameter is closed.
The Ignition 1 Signal parameter is between 10-18 volts .
The Fuel Alcohol Content parameter is less than 90 percent .
The Fuel Tank Level Remaining parameter is more than 10 percent .
The TP Indicated Angle parameter is between 3-70 percent more than the value observed at idle.
OR

Power Enrichment Test Enable:
DTCs P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0120, P0169, P0178, P0179, P0200, P0220, P0300, P0442, P0446, P0452, P0453, P0455, P0496, P1125, P1258, P1516, P2101, P2108, P2135, U0107 are not set.
The Loop Status parameter is closed.
The Ignition 1 Signal parameter is between 10-18 volts .
The Fuel Alcohol Content parameter is less than 90 percent .
The Fuel Tank Level Remaining parameter is more than 10 percent .
The Engine Run Time parameter is more than 30 seconds .
The Power Enrichment parameter is active for more than 1 second .
CONDITIONS FOR SETTING THE DTC

Lean Test:
The PCM detects that the affected HO2S voltage parameter is less than 200 mV for 165 seconds .

OR

Power Enrichment Test:
The PCM detects that the affected HO2S voltage parameter is less than 360 mV for 10 seconds .

ACTION TAKEN WHEN THE DTC SETS
The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
The control module commands the Loop Status open.
CONDITIONS FOR CLEARING THE MIL/DTC
The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Clear the MIL and the DTC with a scan tool.