ESO - Engine System Output Incorrect (Ford)
What does P1170 mean?
The P1170 code means the vehicle's onboard diagnostic system has detected: ESO - Engine System Output Incorrect (Ford). This is a moderate severity code.
Common Symptoms
- Check Engine Light on
- Reduced engine performance
- Multiple other codes may be present
- Possible stalling or rough running
- Failed emissions test
Probable Causes (Ranked by Likelihood)
- Multiple sensor or actuator faults triggering incorrect PCM outputs Very High
- PCM programming error or corruption High
- Major vacuum leak or air metering issue Moderate
- Fuel system malfunction Moderate
- PCM hardware failure Low
Step-by-Step Diagnostic Procedure
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Scan for all stored and pending codes -- fix any other codes first
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Check for technical service bulletins (TSBs) related to PCM reprogramming
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Verify MAF sensor, TPS, and O2 sensor readings are within normal range
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Check for major vacuum leaks and fuel delivery issues
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If no other codes or faults are found, consider PCM reflash or replacement
Frequently Asked Questions
What does Engine System Output Incorrect mean?
P1170 on Ford vehicles is a broad code indicating the PCM has detected that one or more engine system outputs are not matching expected values. It is often a secondary code that accompanies other, more specific fault codes.
Should I fix P1170 first or other codes?
Always fix other codes first. P1170 is often triggered as a result of other faults. Once the primary issues are resolved, P1170 frequently clears on its own.
Could the PCM need reprogramming?
Yes. Ford has issued technical service bulletins for some models requiring a PCM reflash to address P1170. Check with a Ford dealer for applicable TSBs for your specific vehicle year and model.