P0170
Fuel Trim Malfunction (Bank 1)
medium
i Description
The fuel trim on Bank 1 is outside its normal correction range. The ECU can no longer adequately compensate for the air/fuel ratio discrepancy it is detecting.
? Common Causes
- Vacuum leak
- Faulty MAF or O2 sensor
- Fuel pressure issue
- Exhaust leak
- Injector fault
! Symptoms
- Check engine light
- Poor fuel economy
- Rough idle
- Hesitation
# Diagnostic Steps
- Check short-term and long-term fuel trims
- Inspect for vacuum leaks
- Test fuel pressure
- Check MAF and O2 sensors
- Inspect injectors
⚙ Typical Fix
Address the root cause — vacuum leak, sensor fault, or fuel delivery issue.
Parts Needed
Varies based on root cause
Estimated Cost
$100-$500
↔ Related Codes
Q Frequently Asked Questions
You can drive, but performance and fuel economy are affected. Address within a week to prevent catalytic converter damage.
☞ Learn More
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