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1998 Ford Escort Emissions Failure: Troubleshooting OBD2 Codes 0171 and 1131

Model: 1998 Ford Escort Fault Code: P0171 Posted: 2011-03-29 21:47

My 1998 Ford Escort failed emissions testing today, triggering OBD2 diagnostic codes 0171 and 1136. I understand that code 1131 relates to the oxygen (O2) sensor, but I'm unsure if simply replacing the front O2 sensor will resolve both issues. Could there be another underlying cause? What are the most common causes of these two codes together in a 1998 Ford Escort?

Related fault codes
P0171P1131
Comments (1)
Anonymous 2011-03-30 05:14

Replacing the front O2 sensor might help, but vacuum leaks can also trigger both code 0171 and 1131. It's important to check for vacuum hose damage or loose connections before replacing any sensors.