Fuel Trim Cylinder Balance Bank 2 (GM)
What does P1173 mean?
The P1173 code means the vehicle's onboard diagnostic system has detected: Fuel Trim Cylinder Balance Bank 2 (GM). This is a moderate severity code.
Common Symptoms
- Check Engine Light on
- Rough idle or vibration
- Engine misfires on Bank 2
- Poor fuel economy
- Uneven exhaust tone
Probable Causes (Ranked by Likelihood)
- Clogged or leaking fuel injector on Bank 2 Very High
- Intake manifold gasket leak on Bank 2 High
- Low compression on one Bank 2 cylinder Moderate
- Faulty ignition coil or spark plug on Bank 2 Moderate
- Fuel injector driver fault in PCM Low
Step-by-Step Diagnostic Procedure
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Run a cylinder balance test to identify the problem cylinder on Bank 2
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Test fuel injector resistance and spray pattern on Bank 2
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Perform a compression test on Bank 2 cylinders
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Swap ignition coils between Bank 1 and Bank 2 to see if the problem follows
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Check Bank 2 intake runner gaskets for leaks
Frequently Asked Questions
What is the difference between P1172 and P1173?
P1172 indicates a cylinder balance issue on Bank 1, while P1173 indicates the same type of issue on Bank 2. Both codes mean one or more cylinders on the respective bank are not contributing equally to engine power.
Can a coil swap test help diagnose P1173?
Yes. Swapping an ignition coil from the suspected bad cylinder with a known-good cylinder is an excellent diagnostic technique. If the misfire moves to the new cylinder, the coil is the problem.
Is fuel injector cleaning effective?
Professional ultrasonic fuel injector cleaning can restore flow to partially clogged injectors. However, if an injector is electrically failed, leaking internally, or severely clogged, replacement is necessary.