DerekT

Everytime I drive my car, it seems to throw a P0172 and P0175 code on the DIC around every 50 miles or so. Does anybody have any idea as to what the cause of this could be? I did a little research and it says it is the code for running rich, but the only thing I can think that would cause this is my cat back (B&B PRT). Any ideas? anything would be appreciated

Tmyz 2K

what other mods are on the car? longtubes? cats?

DerekT

Nope just a B&B PRT cat-back, and other minor stuff that has nothing to do with the power train. No intake/headers/cats/cam etc etc it is basically stock

Speedratchet

See if this information helps at all.

http://gearchatter.com/viewtopic1059...780661d1bcc414

Mr. Lucky

The CEL doesn't illuminate until the second occurance of either of those codes. If your air filter is dirty, it may be choking the air flow beyond the capability of the PCM to compensate.

DerekT

Well I checked out the filter and it was relatively dirty, so I will get a new one on another day and update. I hope this solves it

Bill Dearborn

There are several things that could cause the codes. Here is the diagnostic from the Service Manual. I edited it to take out the sections in the table where the scan tool is used. You should inspect the other items mentioned in the procedure if the air filter doesn't help.
DTC P0172 or P0175

Circuit Description
The powertrain control module (PCM) controls the air/fuel metering system in order to provide the best possible combination of driveability, fuel economy, and emission control. Fuel delivery is controlled differently during Open and Closed Loop. During Open Loop the PCM determines fuel delivery based on sensor signals without oxygen sensor (O2S) input. During Closed Loop, the oxygen sensor inputs are added and used by the PCM to calculate short and long term fuel trim fuel delivery adjustments. If the O2S indicate a lean condition, the fuel trim values will be above 0 percent. If the O2S indicate a rich condition, the fuel trim values will be below 0 percent. Short term fuel trim values change rapidly in response to the heated oxygen sensor (HO2S) voltage signals. Long term fuel trim makes coarse adjustments in order to maintain an air/fuel ratio of 14.7:1. The fuel trim diagnostic will conduct a test to determine if a rich failure actually exists, or if excessive vapor from the evaporative emission (EVAP) canister is causing a rich condition. If the PCM detects an excessively rich condition, DTC P0172 or P0175 sets.

Conditions for Running the DTC
• DTCs P0101, P0103, P0108, P0135, P0137, P0141, P0200, P0300, P0410, P0420, P0430, P0440, P0442, P0443, P0446, P0449, P0506, P0507 or P1441 are not set.
• The engine coolant temperature (ECT) is between 75-115°C (167-239° F).
• The intake air temperature (IAT) is between -20 to +90°C (4-194°F).
• The manifold absolute pressure (MAP) is between 26-90 kPa (3.7-13 psi).
• The vehicle speed is less than 137 km/h (85 mph).
• The engine speed is between 400-3,000 RPM.
• The barometric pressure (BARO) is more than 74 kPa (10.7 psi).
• The mass airflow (MAF) is between 5-90 g/s.
• The fuel level is more than 10 percent.
• The throttle position (TP) is less than 90 percent.

Conditions for Setting the DTC
• The average long term fuel trim value is below -13 percent.
• All of the above conditions are present for 40 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.

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.

Diagnostic Aids
• Fuel contamination, such as water or alcohol will effect fuel trim.
• A malfunctioning mass air flow sensor can cause a rich condition and set this DTC. Refer to DTC P0101 .
• Use a scan tool in order to review Failure Records. If an intermittent condition is suspected , refer to Intermittent Conditions .

Test Description
The numbers below refer to the step numbers on the diagnostic table.
5. If conditions were not corrected, refer to Fuel System Diagnosis for a possible fuel problem.
6. An EVAP canister that is saturated will cause a rich condition. If the conditions were not corrected, a worn cam, worn intake or exhaust valves, or other engine mechanical failure may be the problem.
Step Action Values Yes No
4 1. Turn OFF engine.
2. Visually and physically inspect the following items:
o The EVAP lines and components for damage or blockage--Refer to Evaporative Emissions (EVAP) Hose Routing Diagram .
o The inlet screen of the MAF sensor for blockage
o The vacuum hoses for splits, kinks, and proper connections--Refer to Emission Hose Routing Diagram .
o The air intake duct for being collapsed or restricted
o The air filter for being dirty or restricted
o Inspect for objects blocking the throttle body.
Did you find and correct the condition? -- Go to Step 7
Go to Step 6

5
1. Turn OFF engine
2. Inspect the HO2S for proper installation.
3. Inspect to ensure that the electrical connectors and the wires are secure and not contacting the exhaust system.
4. Test for continuity between the signal circuit and the low reference circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition? -- Go to Step 7
Go to Fuel System Diagnosis

6
Inspect for the following:
• Excessive fuel in the crankcase
• Proper operation of the fuel pressure regulator--Refer to Fuel System Diagnosis .
• All injectors are functioning properly--Refer to Fuel Injector Coil Test .
Did you find and correct the condition? -- Go to Step 7
Go to Symptoms - Engine Mechanical in Engine Mechanical


Bill