System Too Lean at Higher Load Bank 1
The P2191 code means the vehicle's onboard diagnostic system has detected: System Too Lean at Higher Load Bank 1. This is a serious severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- moderate
- Estimated cost
- $50 - $700 (vacuum leak or a dirty sensor commonly; fuel-delivery parts cost more)
Best-selling code reader on Amazon. Reads and clears check engine codes on any 1996+ vehicle. Under $30.
Essential for diagnosing sensor codes, checking voltage, and testing circuits. Under $15 and pays for itself on the first job.
Affiliate links — we earn a commission at no extra cost to you.
Common Symptoms
- Check Engine Light on
- Rough idle, hesitation, or reduced power
- Fuel economy worse than normal
- Fuel trim values far from zero on a scan tool
Probable Causes (Ranked by Likelihood)
- Unmetered air entering after the MAF (vacuum/intake leak) - the most common cause of a lean code High
- Dirty or failing MAF sensor misreporting airflow High
- Fuel delivery problem - weak pump, clogged filter, or dirty injectors Moderate
- Failing oxygen sensor skewing the correction Moderate
Frequently Asked Questions
What does P2191 mean?
P2191 is a generic OBD-II code defined by SAE J2012 as "System Too Lean at Higher Load Bank 1". It means the control module detected a fault in this circuit
Can I keep driving with P2191?
Yes for normal use, but get it diagnosed - the system is running on a fallback strategy and a small wiring fault left alone tends to become a bigger one.
Does P2191 mean the same thing on every car?
Yes. P2191 is in the generic (SAE J2012) range, so the definition is standardized across manufacturers. The specific component location and repair procedure still vary by vehicle - check your service information.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
-
Read short and long-term fuel trims at idle and at higher RPM - a lean condition that improves with RPM points at a vacuum leak.
-
Smoke-test the intake for leaks.
-
Inspect and, if needed, clean the MAF sensor.
-
Check fuel pressure against spec before replacing sensors.
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
- Cross-checked against the SAE J2012:2002 DTC table (2026-08-27)archived scan of the SAE standard — readable copy, not SAE’s current edition
Commonly Affected Vehicles
- All OBD-II vehicles - this is a generic (SAE J2012) code with the same meaning across makes
Related Codes
Explore More
Was this helpful?
Send this to whoever is fixing the car — your mechanic, or the person asking what the light means.