P0175
DTC P0175 Fuel Trim - System Too Rich (Bank 2)
Circuit Description
To provide the best possible combination of driveability, fuel economy, and emission control, a "closed loop" air/fuel metering system is used. While in "closed loop", the engine control module (ECM) monitors the Bank 1 HO2S1 and Bank 2 HO2S1 signals and adjusts fuel delivery based upon the HO2S signal voltages. A change made to fuel delivery will be indicated by the long and short term fuel trim values which can be monitored with a Tech 2. Ideal fuel trim values are around 0%; if the HO2S signals are indicating a lean condition the ECM will add fuel, resulting in fuel trim values above 0%. If a rich condition is detected, the fuel trim values will be below 0%, indicating that the ECM is reducing the amount of fuel delivered. ECM calculates long term fuel trim and short term fuel trim in closed loop condition. If sum of long term fuel trim and short term fuel trim is exceeds the rich limit and long term fuel trim reaches rich limit, DTC P0175 will be set.
The ECM's maximum authority to control long term fuel trim allows a range between -15% (automatic transmission) and +20%. The ECM's maximum authority to control short term fuel trim allows a range between -11% and +20%. The ECM monitors fuel trim under various engine speed/load fuel trim cells before determining the status of the fuel trim diagnostic.
Conditions for Setting The DTC
Calculation of the sum of long term fuel trim and short term fuel trim.
- No related DTCs.
- Engine is running in "Closed Loop".
- Engine speed is above 550 rpm.
- Engine Load is above 31.
- Engine coolant temperature is above 30 °C.
- Intake air temperature is between -10 °C and 60 °C.
- BARO is above 72 kpa.
- Evap Leak check is not active.
Monitoring condition for Long term fuel trim.
- No related DTCs.
- Engine is running in "closed loop".
- Engine running time is above 120 seconds.
- Engine speed is above 2000 rpm.
- Engine load is above 40.
- Engine coolant temperature is above 75 °C.
- Intake air temperature is between -10 °C and 80 °C.
- BARO is above 72 kpa.
Action Taken When the DTC Sets
- The ECM will illuminate the malfunction indicator lamp (MIL) after the second consecutive trip in which the failure is detected.
- The ECM will store conditions which were present when the DTC was set as Freeze Frame and in the Failure Records data.
IMPORTANT: DTC is stored in memory as an historical data entry. If there is no freeze frame data, inspection is required. If no problems are discovered during inspection, clear the DTC data from memory.
Conditions for Clearing The MIL/DTC
- The ECM will turn the MIL "OFF" on the third consecutive trip cycle during which the diagnostic has been run and the fault condition is no longer present.
- DTC P0175 can be cleared by using the Tech 2 "Clear Info" function or by disconnecting the ECM battery feed.
Diagnostic Aids
Check for the following conditions:
- Poor connection at ECM - Inspect harness connectors for backed -out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connection.
- Damaged harness - Inspect the wiring harness for damage. If the harness appears to be OK, observe the Bank 2 HO2S1 display on the Tech 2 while moving connectors and wiring harnesses related to the engine harness. A change in the display will indicate the location of the fault.
Steps 1 - 3:
Steps 4 - 9:
Steps 10 - 14:
Steps 15 - 20:
Steps 21 - 25:
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Chart.
2. DTCs other than P0172 and P0175 may indicate a condition present which may cause a lean condition. If this is the case, repairing the condition which caused the other DTC will most likely correct the DTC P0172/P0175.
4. If the DTC P0175 test passes while the Failure Records conditions are being duplicated, the rich condition is intermittent. Refer to Diagnostic Aids or Symptoms for additional information on diagnosing intermittent problems.