P1174

DTC P1174

DTC DESCRIPTOR

DTC P1174
Fuel Trim Cylinder Balance

DIAGNOSTIC FAULT INFORMATION
Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection

CIRCUIT/SYSTEM DESCRIPTION
The Fuel Trim Cylinder Balance diagnostic detects a rich or a lean cylinder-to-cylinder air/fuel ratio imbalance. The diagnostic monitors the pre-catalyst heated oxygen sensor (HO2S) signal's frequency and amplitude characteristics by calculating an accumulated voltage over a predetermined sample period. An imbalance is indicated when the accumulated voltage is consistently higher than the desired value.

CONDITIONS FOR RUNNING THE DTC
- DTCs P0030, P0053, P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0116, P0117, P0118, P0120, P0121, P0122, P0123, P0125, P0128, P0131, P0132, P0133, P0134, P0135, P0151, P0152, P0153, P0154, P0155, P0220, P0222, P0223, P0201-P0204, P0300, P0301-P0304, P0442, P0443, P0446, P0449, P0451, P0452, P0453, P0454, P0455, P0496, P060D, P060E, P1133, P1516, P1680, P1681, P2101, P2119, P2120, P2122, P2125, P2127, P2128, P2135, P2138, P2176, P2A00, P2A01, P2A03 are not set.
- The device control is not active.
- The intrusive diagnostics is not active.
- The engine overspeed protection is not active.
- The traction control is not active.
- The fuel control is in air-fuel Closed Loop.
- The system voltage is greater than 10 volts, or less than 18 volts.
- The engine run time is greater than 50 seconds.
- The engine coolant temperature (ECT) is greater than 10°C (50°F).
- The engine speed is greater than 1,000 RPM, but less than 4,000 RPM.
- The mass air flow is greater than 7 g/s, but less than 400 g/s.
- DTC P1174 runs continuously when the above conditions are met.

CONDITIONS FOR SETTING THE DTC
The HO2S voltage crosses 450 mV more than 4 times during the current sample period.

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
The Fuel Trim Cylinder Balance diagnostic is very sensitive to HO2S design. A non-OE sensor may set a false DTC.

CIRCUIT/SYSTEM TESTING
1. Diagnose any other DTCs that are set. refer to Diagnostic Trouble Code (DTC) List - Vehicle. Diagnostic Trouble Code Descriptions
2. Inspect the air induction system for the following conditions:
- Modified, damaged, leaking, or restricted components
- Dirty, missing, or deteriorating air filter element
3. Inspect the crankcase ventilation system for proper operation.
4. Inspect the vacuum hoses for splits, kinks, and proper connections.
5. Inspect for vacuum leaks at the intake manifold, the throttle body, and the injector O-rings.
6. Test for fuel contamination. Refer to Alcohol/Contaminants-in-Fuel Diagnosis. Alcohol/Contaminants-in-Fuel Diagnosis
7. Test for excessive fuel in the crankcase.
8. Test the fuel injectors. Refer to Fuel Injector Diagnosis. Fuel Injector Diagnosis
9. Test the ignition system for proper operation. Refer to Electronic Ignition (EI) System Diagnosis. Electronic Ignition (EI) System Diagnosis
10. Test for a restricted, damaged, leaking, or modified exhaust system. Refer to Symptoms - Exhaust System. Symptom Related Diagnostic Procedures
11. Test the engine for any mechanical conditions which could cause an air/fuel imbalance. Refer to Symptoms - Engine. Symptom Related Diagnostic Procedures

REPAIR INSTRUCTIONS

IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Air Cleaner Assembly Replacement
- Air Cleaner Element Replacement
- Air Cleaner Outlet Resonator Replacement
- Fuel Injector Replacement
- Fuel System Cleaning
- Fuel Tank Draining Procedure
- Ignition Coil(s) Replacement
- Intake Manifold Replacement
- Spark Plug Replacement
- Throttle Body Assembly Replacement Verification Tests