System Too Rich (Bank 2)
The engine control module (ECM) detected a rich condition in bank 2.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The engine is getting too much fuel and not enough air, which can cause poor performance and emissions issues.
What the computer is actually seeing
The ECM monitors the air-to-fuel ratio using data from the oxygen sensors, and if the sensor reads a value indicating a rich mixture (too much fuel), it triggers this code.
What a healthy reading looks like
Oxygen sensor voltage should typically fluctuate between 0.1V and 0.9V; anything consistently above 0.9V indicates a rich mixture.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Inspect wiring and connectors to the fuel injectors and oxygen sensor for damage or poor connection. Decision: If damaged, repair or replace. If okay, proceed to step 2.
- 22. Check fuel pressure with a gauge. Should be within manufacturer specs (often 40-65 PSI). Decision: If pressure is too high, check the fuel pressure regulator. If pressure is normal, proceed to step 3.
- 33. Inspect the oxygen sensor on bank 2. Use a multimeter to check voltage; should fluctuate. Decision: If not fluctuating correctly, replace the sensor. If it is, proceed to step 4.
- 44. Run a smoke test to check for intake air leaks. Decision: If leaks are found, repair them. If no leaks, continue checking other potential causes.
Common causes
- Faulty fuel injectors
- Leaking fuel pressure regulator
- Excessive fuel pressure
- Bad oxygen sensor
- Intake air leaks
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's advisable to fix it soon as it can lead to increased emissions and poor performance.
Will this code come back after I clear it?
If the underlying issue isn't resolved, yes, it will return.
Why do I see this code paired with P0172?
P0172 indicates a rich condition in bank 1; they often occur together due to similar issues in fuel delivery or air intake.
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