Symptoms
For this DTC, the malfunction indicator light (MIL) illuminates. There may be other symptoms.
Causes
Potential causes for a P2197 code include:
- Malfunction of the oxygen sensor (O2) or A/F ratio sensor or sensor heater
- Open or shorted O2 sensor circuit (wiring, harness)
- Fuel pressure or fuel injector issue
- Faulty PCM
- Intake air leaks or engine vacuum leaks
- Faulty fuel injector(s)
- Fuel pressure too high or too low
- PCV system leak/failure
- Faulty A/F sensor relay
- MAF sensor malfunction
- ECT sensor malfunction
- Fuel pressure too low
- Fuel leak
- Air intake in the air intake system
Diagnostic Steps and Possible Solutions
Use a scan tool to obtain sensor readings and monitor short-term and long-term fuel trim values and O2 sensor or air/fuel ratio readings. Also, look at freeze frame data to see the conditions when the code was set. This should help determine if the AF O2 sensor is functioning correctly. Compare with manufacturer values.
If you don’t have access to a scan tool, you can use a multimeter and probe the terminals of the O2 sensor wiring connector again. Check for shorts to ground, shorts to power, open circuits, etc. Compare the specifications with the manufacturer’s specifications.
Visually inspect the wiring and connectors leading to the sensor, look for loose connectors, rubbed/chafed wires, melted wires, etc. Repair as necessary.
Visually inspect the vacuum lines. You can also test for vacuum leaks using propane or carburetor cleaner along the hoses while the engine is running; if the RPM changes, you’ve likely found the leak. Be very careful if you do this, and have a fire extinguisher on hand in case of issues. For example, on many Ford vehicles, the hose from the PCV to the throttle body can melt, causing codes P2195, P2197, P0171, and/or P0174. If a vacuum leak turns out to be the problem, it would be wise to replace all vacuum lines if they are aging, becoming brittle, etc.
Use a digital volt ohmmeter (DVOM) to check the proper operation of other mentioned sensors such as MAF, IAT.
Perform a fuel pressure test, check readings against manufacturer specifications.
If you’re on a tight budget and have an engine with more than one bank and the issue is only on one bank, you can swap the sensor from one bank to the other, clear the code, and see if the code follows to the other bank. This would tell you that it’s the sensor/heater itself that has failed.
Check for any outstanding technical service bulletins (TSB) for your vehicle; in some cases, the PCM may be recalibrated to resolve this issue (not a common solution, however). TSBs might also call for sensor replacement.
When replacing oxygen/AF sensors, make sure to use high-quality sensors. In many cases, non-OEM sensors are of lower quality and will not function properly. We strongly recommend sticking with OEM brand replacements.