The function of the fuel cylinder balance diagnostic is to check for fuel mixture imbalances between a rich and lean cylinder. It monitors the frequency and amplitude characteristics of the oxygen sensor (HO2S) signal upstream of the catalytic converter. Therefore, it calculates the voltage that builds up over a predetermined time.
When an unbalance is found, it is because several samples of the accumulated voltage turn out to have inconsistencies higher than the expected value. After that, the diagnostic code P1174 OBDII will be set.
Other DTCs are stored, which indicate problems with the vehicle's Oxygen Sensors and combustion system.
Problems with fuel efficiency.
Causes of OBD2 P1174
The causes of storing the P1174 OBD2 fault code are:
One or more fuel injectors may be clogged.
An oxygen sensor may be defective.
The motor may have other mechanical failures.
Possible solutions of the DTC code P1174
The steps to troubleshoot the OBDII DTC P1174 are:
See Technical Service Bulletins.
By using an automotive scanner, check if other fault codes are stored. In this case, diagnose any DTCs according to the order displayed on the scanner, especially if they are related to ignition faults.
If you recently replaced an Oxygen Sensor, check that it is OE (Original Equipment). Otherwise, the cylinder balance diagnostic becomes very sensitive so this code can be set.
Inspect induction system components for damaged hoses causing leaks or other conditions. Repair as required.
Check the Oxygen Sensors for circuit damage. Any burned wires or corroded connectors should be repaired or replaced as necessary.
Check vacuum hoses for damage or improper connections causing leaks at the intake manifold, throttle body, or injector connections. Correct as applicable.
Check fuel injectors for common damage. Replace as required.