P0171 on a 2010 Cadillac Srx

P0171 means the engine computer is adding more fuel than normal on bank 1 because it sees too much air or not enough fuel.

Not your vehicle? See general P0171 info.

Most common causes on the 2010 Cadillac Srx

Ranked from 474 NHTSA owner complaints filed for this vehicle.

Sort by:

1
Weak fuel pump / low fuel delivery pressure
Medium severity
One owner described the car struggling to get fuel right away with a rough idle at stops — a classic lean/fuel-starvation symptom.
Reported in 1 NHTSA complaint
Parts:fuel pump
2
Throttle body air-metering fault
Medium severity
A throttle body issue was diagnosed after the vehicle lost power and wouldn't accelerate past idle speed, consistent with an air-metering problem that can also skew fuel trims lean.
Reported in 1 NHTSA complaint
Parts:throttle body
3
Vacuum or intake air leak
Medium severity
Unmetered air entering downstream of the MAF sensor is the most common cause of a lean-bank code on this class of vehicle.
Common cause
4
Dirty or failing MAF sensor
Medium severity
An under-reporting MAF sensor causes the ECM to add too little fuel, producing a lean condition.
Common cause
Parts:MAF sensor
5
Clogged fuel filter
Low severity
Restricted fuel flow reduces delivery pressure at higher demand, contributing to a lean condition.
Common cause
Parts:fuel filter
6
Stuck-open PCV valve
Low severity
A PCV valve stuck open draws unmetered air into the intake and is a common lean-code contributor.
Common cause
Parts:PCV valve
7
Intake manifold gasket leak
Medium severity
A leaking manifold gasket is a classic unmetered-air source producing a persistent lean-bank code.
Common cause
Parts:intake manifold gasket

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These causes are aggregated from NHTSA owner complaints and general repair knowledge — this is not a diagnosis. P0171 on your car still needs shop confirmation before any repair.

Common symptoms

Check engine light
Rough idle
Hesitation
Surging idle
Poor fuel economy

What to check before replacing parts

Review short- and long-term fuel trims on bank 1

Look for: High positive trims (commonly worse at idle, improving with RPM) mean the computer is adding fuel to compensate for excess air or insufficient fuel — that pattern is this code's fingerprint.

Smoke-test the intake

Look for: Smoke escaping (or a hiss you can hear) at intake boots, gaskets, or vacuum hose connections confirms unmetered air is entering after the MAF sensor, which is the most common cause of a lean code.

Inspect the PCV hoses and valve

Look for: A cracked, split, or disconnected PCV hose, or a PCV valve stuck open, draws in extra unmetered air the same way a vacuum leak does.

Clean and test the MAF sensor

Look for: Visible dirt or oil film on the sensor element, or a grams/second reading that doesn't track expected airflow for RPM, means the MAF is under-reporting air and causing the computer to under-fuel.

Verify fuel pressure

Look for: Pressure below spec (weak pump, clogged filter, failing regulator) starves the engine of fuel and produces the same lean trim pattern as a vacuum leak — rule it out before chasing leaks.

Rather have a pro handle it? Find a vetted local mechanic.

Matching symptoms

Car Runs Rough