P0173: Fuel Trim Malfunction (Bank 2)
Can you still drive? Drive with caution. Extended driving with fuel trim issues can cause engine damage or catalytic converter failure.
What Does P0173 Mean?
Code P0173 indicates that the fuel trim values on bank 2 have gone beyond the acceptable correction range. The ECM continuously adjusts the air-fuel mixture, and when it cannot compensate enough to maintain the correct ratio, this code is triggered. This often points to a significant vacuum leak, fuel delivery problem, or sensor issue on that bank.
Need to read your codes?
An OBD-II scanner lets you read and clear diagnostic trouble codes from your vehicle's computer. Most scanners work with any car made after 1996.
Browse OBD-II Scanners on AmazonCommon Causes
- Large vacuum leak on bank 2 intake
- Faulty mass airflow sensor
- Clogged or failing fuel injectors
- Weak fuel pump
- Leaking fuel pressure regulator
Symptoms
- Check engine light on
- Rough or unstable idle
- Poor acceleration
- Decreased fuel economy
- Engine may stall
Diagnostic Steps
- 1Read freeze frame data and check long-term fuel trim values
- 2Perform a smoke test to detect vacuum leaks
- 3Clean or test the mass airflow sensor
- 4Check fuel pressure at the rail
- 5Test fuel injector flow rates on bank 2
- 6Inspect intake manifold gaskets
Recommended Parts & Tools
MAF sensor cleaner
fuel injector cleaner
smoke machine leak detector
Estimated Repair Cost
| Type | Estimated Cost |
|---|---|
| Total Repair Cost Range | $100 - $800 |
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Chat with AI About P0173Commonly Affected Vehicles
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Frequently Asked Questions
What are fuel trims?
Fuel trims are adjustments the ECM makes to the fuel injector pulse width to maintain the ideal 14.7:1 air-fuel ratio. Positive trims mean the ECM is adding fuel (lean condition), negative trims mean it is reducing fuel (rich condition).
Can a dirty air filter cause P0173?
A severely restricted air filter can affect airflow readings, but it is more commonly caused by vacuum leaks, a dirty MAF sensor, or fuel delivery problems.
Is P0173 the same as running lean?
Not necessarily. P0173 means the fuel trim correction is out of range, which could be caused by either a lean or rich condition that the ECM cannot compensate for.
Community Fix Reports
Community reports are user-submitted and not verified by Auto AI Buddy. Results may vary.
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