What Does P2179 Mean?
The PCM detects the fuel mixture is too lean (excess air or insufficient fuel) specifically during off-idle conditions on Bank 2. This indicates the fuel trim corrections have exceeded normal limits when the throttle is opened beyond idle on the opposite bank from Bank 1.
Common Causes
35%
Vacuum leak in intake manifold or hoses affecting Bank 2
25%
Faulty or clogged fuel injectors on Bank 2
20%
Low fuel pressure or weak fuel pump
12%
Exhaust leak before Bank 2 oxygen sensor
8%
Mass airflow sensor reading high causing system-wide lean condition
Diagnostic Steps
1
Step 1: Use scan tool to monitor short-term and long-term fuel trims on Bank 2 at various RPMs
2
Step 2: Perform smoke test or propane enrichment test focusing on Bank 2 side of intake
3
Step 3: Test fuel pressure at idle and under load; compare to specifications
4
Step 4: Visually inspect Bank 2 exhaust manifold and connections for leaks before O2 sensor
5
Step 5: Compare Bank 1 and Bank 2 fuel trim values to determine if issue is bank-specific or system-wide
Estimated Repair Cost
$100 - $800
Parts + labor, varies by vehicle and location
The PCM detects the fuel mixture is too lean (excess air or insufficient fuel) specifically during off-idle conditions on Bank 2. This indicates the fuel trim corrections have exceeded normal limits when the throttle is opened beyond idle on the opposite bank from Bank 1.
The most common cause of P2179 (System Too Lean Off Idle Bank 2) is: Vacuum leak in intake manifold or hoses affecting Bank 2
Typical repair costs for P2179 range from $100 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle may hesitate or lack power during acceleration. Safe to drive short distances but reduced performance and fuel economy.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P2179 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel System and Emissions
Difficulty
Type
Generic (SAE)
Recommended Tools
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