Cause
Contaminated or failing mass air flow sensor
The sensor measuring how much air the engine is actually drawing. Contamination — oil from an over-oiled performance filter is the classic — makes it read low, so the module fuels for less air than is arriving and the engine runs lean while nothing is leaking. Worth suspecting on any lean code where a vacuum leak cannot be found.
Typically an easy fix. Often worth checking before paying anyone to look.
Some of these codes mean you should stop driving
2 of the 22 codes this can cause indicate a fault where continuing to drive risks damage or is unsafe. Which one you have matters more than the cause does — read the code's own page before deciding.
Codes this can cause (22)
Codes where this is a likely explanation first, rather than merely a possible one.
- P0068 Manifold Absolute Pressure/Mass Air Flow — Throttle Position Correlation Likely for this code Stop driving High
- P0100 Mass or Volume Air Flow Sensor A Circuit Likely for this code High
- P0101 Mass or Volume Air Flow Sensor A Circuit Range/Performance Likely for this code High
- P0102 Mass or Volume Air Flow Sensor A Circuit Low Likely for this code High
- P0103 Mass or Volume Air Flow Sensor A Circuit High Likely for this code High
- P0170 Fuel Trim Malfunction — Bank 1 Likely for this code High
- P0171 System Too Lean — Bank 1 Likely for this code High
- P0172 System Too Rich — Bank 1 Likely for this code High
- P0173 Fuel Trim Malfunction — Bank 2 Likely for this code High
- P0174 System Too Lean — Bank 2 Likely for this code High
- P0175 System Too Rich — Bank 2 Likely for this code High
- P2177 System Too Lean Off Idle Bank 1 Likely for this code Moderate
- P2199 Intake Air Temperature Sensor 1/2 Correlation Likely for this code Moderate
- P0104 Mass or Volume Air Flow Sensor A Circuit Intermittent Moderate
- P0110 Intake Air Temperature Sensor 1 Circuit Bank 1 Moderate
- P0131 O2 Sensor Circuit Low Voltage — Bank 1 Sensor 1 Moderate
- P0132 O2 Sensor Circuit High Voltage — Bank 1 Sensor 1 Moderate
- P0300 Random/Multiple Cylinder Misfire Detected Stop driving High
- P2073 Manifold Absolute Pressure/Mass Air Flow — Throttle Position Correlation at Idle Moderate
- P2179 System Too Lean Off Idle Bank 2 Moderate
- P2191 System Too Lean at Higher Load Bank 1 Moderate
- P2280 Air Flow Restriction/Air Leak Between Air Filter and Mass Air Flow Sensor Bank 1 Moderate
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Others who found this
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
Sign in or create an account to add what you found about Contaminated or failing mass air flow sensor.