For 1990-2009 cars only
Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC P1174: Air Fuel Imbalance Bank 1Circuit/System Description
The air fuel imbalance monitor (AFIM) diagnostic detects a rich or lean cylinder to cylinder air/fuel ratio imbalance in each bank. 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 multiple samples of the accumulated voltage are consistently higher than the desired value.
Conditions for Running the DTC
| • | DTCs P0030, P0036, P0050, P0053, P0059, P0101, P0102, P0103, P0106, P0107, P0108, P0117, P0118, P0128, P0131, P0132, P0133, P0134, P0135, P0151, P0152, P0153, P0154, P0155, P0201-P0206, P0300, P0301-P0306, P0411, P0412, P0418, P0442, P0443, P0446, P0449, P0452, P0453, P0454, P0455, P0496, P1133, P1153, P1516, P2101, P2119, P2120, P2125, P2135, P2138, P2176, P2431, P2432, P2433, P2440, P2A00, P2A03 are not set. |
| • | The device control is not active. |
| • | The intrusive diagnostics are not active. |
| • | The engine overspeed protection is not active. |
| • | The power take-off (PTO) 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. |
Conditions for Setting the DTC
Multiple samples of the pre-catalyst HO2S accumulated voltage are consistently higher than the desired value.
Action Taken When the DTC Sets
DTC P1174 is a type B DTC.
Conditions for Clearing the MIL/DTC
DTC P1174 is a type B DTC.
Diagnostic Aids
| • | The fuel trim cylinder balance diagnostic is very sensitive to heated oxygen sensor (HO2S) design. A non-OE sensor or an incorrect part number may set a false DTC. |
| • | Monitoring the misfire current counters, or misfire graph, may help to isolate the cylinder that is causing the condition. |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Special Tools Required
| • | J 34730-1A Fuel Pressure Gage |
| • | J 39021 Fuel Injector Coil and Balance Tester |
| • | J 39021-210 Injector Tester Adapter Box |
| • | J-39021-450 Fuel Injector Harness Adapter |
Circuit/System Testing
- Read and record the Freeze Frame/Failure Records data taking note of the speed and load at which the DTC set.
- Diagnose any other DTCs that are set. Refer to Diagnostic Trouble Code (DTC) List - Vehicle .
- With the engine idling and the transmission in the Park or Neutral position, observe the manifold absolute pressure (MAP) sensor parameter. The MAP sensor parameter should be between 19-42 kPa.
- Inspect the air induction system for modified, damaged, leaking, or restricted components.
- Inspect the crankcase ventilation system for improper operation.
- Inspect the vacuum hoses for splits, kinks, and improper connections.
- Inspect for vacuum leaks at the intake manifold, the throttle body, and the injector O-rings.
- Test for a restricted, damaged, leaking, or modified exhaust system from the catalytic converter forward. Refer to Symptoms - Engine Exhaust .
- Test the fuel injectors for improper operation. Refer to Fuel Injector Diagnosis .
- Test for fuel contamination. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
- Test for excessive fuel in the crankcase due to leaking injectors.
- Test the ignition system for improper operation. Refer to Electronic Ignition (EI) System Diagnosis .
- Test the engine for any mechanical conditions such as sticking valves, lifters, etc., which could alter the flow into the combustion chamber. Refer to Symptoms - Engine Mechanical .
| ⇒ | If the MAP sensor parameter is not between 19-42 kPa, refer to DTC P0106 or DTC P0107 or P0108 . |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verify the repair under the same speed and load as noted in the Freeze Frame/Failure Records data recorded during testing.
