Dirty or faulty mass airflow (MAF) sensor that over-reports airflow (both sources; over-oiled aftermarket air filters can foul it, per OBD-Codes.com). Fuel pressure too high: stuck fuel pressure regulator or pinched/restricted fuel return line (RepairPal); OBD-Codes.com lists fuel pressure or delivery problems. Leaking or shorted fuel injectors. Faulty MAP sensor or its vacuum line, or low engine vacuum from mechanical problems such as a slipped timing chain/belt or head gasket leak (RepairPal). Faulty coolant temperature or intake air temperature sensor, or a thermostat stuck open, so the engine thinks it is still cold (RepairPal). Faulty throttle position sensor (RepairPal). Faulty oxygen sensor, for example an intermittent heater (RepairPal). PCM software needing an update (RepairPal). Vacuum leak (listed by OBD-Codes.com; see the note in the FAQ).

Clean or replace the MAF sensor. Replace a stuck fuel pressure regulator or repair a restricted return line. Clean or replace leaking fuel injectors. Replace a faulty MAP, coolant temperature, intake air temperature or throttle position sensor. Replace a thermostat stuck open. Repair vacuum hoses or the MAP vacuum line. Install a PCM software update if the manufacturer has one. Repair engine mechanical problems such as timing or head gasket faults.

P0175⛽ Fuel and air metering / fuel trimStop and fix promptly

P0175: System Too Rich, Bank 2 (Meaning, Causes, Fixes)

Q: What does P0175 mean?

P0175 means the engine computer has detected that bank 2 of the engine is running rich (too much fuel, not enough air) and it has already pulled out as much fuel as it is allowed to. Common causes include a dirty or faulty mass airflow (MAF) sensor, high fuel pressure from a stuck regulator or pinched return line, leaking injectors, and faulty MAP, coolant temperature or throttle position sensors. Engines run best at about 14.7 parts air to 1 part fuel. The PCM (engine computer) watches the oxygen sensors and trims fuel up or down to hold that ratio. RepairPal explains that P0175 sets when the long-term fuel trim has had to subtract a lot of fuel (it gives roughly -15% to -30% as the range where the rich codes set) and the computer still cannot correct the mixture. Bank 2 is the side of a V6, V8 or V10 that does not contain cylinder 1, so P0175 mostly appears on V-engines, although RepairPal notes some inline engines (for example some BMW and Lexus engines) split their cylinders into banks too. P0172 is the same fault on bank 1, and the two often appear together, which points to a cause shared by both banks such as the MAF sensor or fuel pressure. Note that OBD-Codes.com's page title says 'Bank 1', but its technical description and text say bank 2, which matches the standard definition and RepairPal.

Q: Can I keep driving with P0175?

Stop and fix promptly. Get this diagnosed soon. RepairPal rates P0175 'Urgent', meaning it can lead to severe damage or be unsafe, while OBD-Codes.com says you will most likely not notice any drivability problems. A rich mixture sends extra unburned fuel and carbon monoxide into the exhaust and can cause misfires, which in turn can overheat and damage the catalytic converter. If the engine misfires badly, the check engine light flashes, or you smell strong fuel, stop driving and have it checked.

Reviewed 2026-10-22 · Based on 2 cited source(s)

What P0175 means

Engines run best at about 14.7 parts air to 1 part fuel. The PCM (engine computer) watches the oxygen sensors and trims fuel up or down to hold that ratio. RepairPal explains that P0175 sets when the long-term fuel trim has had to subtract a lot of fuel (it gives roughly -15% to -30% as the range where the rich codes set) and the computer still cannot correct the mixture. Bank 2 is the side of a V6, V8 or V10 that does not contain cylinder 1, so P0175 mostly appears on V-engines, although RepairPal notes some inline engines (for example some BMW and Lexus engines) split their cylinders into banks too. P0172 is the same fault on bank 1, and the two often appear together, which points to a cause shared by both banks such as the MAF sensor or fuel pressure. Note that OBD-Codes.com's page title says 'Bank 1', but its technical description and text say bank 2, which matches the standard definition and RepairPal.

Severity: can I keep driving?

Stop and fix promptly

Get this diagnosed soon. RepairPal rates P0175 'Urgent', meaning it can lead to severe damage or be unsafe, while OBD-Codes.com says you will most likely not notice any drivability problems. A rich mixture sends extra unburned fuel and carbon monoxide into the exhaust and can cause misfires, which in turn can overheat and damage the catalytic converter. If the engine misfires badly, the check engine light flashes, or you smell strong fuel, stop driving and have it checked.

Common symptoms

Check engine light on
Often no other noticeable symptoms
Lack of power on acceleration, 'coughing' or misfiring (per RepairPal)
Rough idle, especially when warm or stopped at a light (per RepairPal)
Fuel smell or a rotten-egg smell from the exhaust
Other codes such as P0172 (bank 1 rich) or P0300 (random misfire)

Likely causes

Roughly most to least common, based on the sources below. Your vehicle may differ.

Dirty or faulty mass airflow (MAF) sensor that over-reports airflow (both sources; over-oiled aftermarket air filters can foul it, per OBD-Codes.com)
Fuel pressure too high: stuck fuel pressure regulator or pinched/restricted fuel return line (RepairPal); OBD-Codes.com lists fuel pressure or delivery problems
Leaking or shorted fuel injectors
Faulty MAP sensor or its vacuum line, or low engine vacuum from mechanical problems such as a slipped timing chain/belt or head gasket leak (RepairPal)
Faulty coolant temperature or intake air temperature sensor, or a thermostat stuck open, so the engine thinks it is still cold (RepairPal)
Faulty throttle position sensor (RepairPal)
Faulty oxygen sensor, for example an intermittent heater (RepairPal)
PCM software needing an update (RepairPal)
Vacuum leak (listed by OBD-Codes.com; see the note in the FAQ)

Diagnostic steps you can do

⚠ Before you start

Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.

Read all stored codes and freeze-frame data. If P0172 is also set, look for a cause that affects both banks, such as the MAF sensor or fuel pressure. Fix any misfire, sensor or fuel codes first.
Check the air filter and its housing. Replace a dirty filter, and if you use an oiled aftermarket filter, make sure it is not over-oiled.
Clean the MAF sensor with spray made for MAF sensors or electronics, without touching the sensing element, and let it dry fully before reinstalling. RepairPal notes cleaning may only help for a while if the sensor is failing.
Inspect vacuum and PCV hoses, and the fuel lines for cracks, leaks or pinches.
With a scan tool, watch long-term fuel trim for bank 2 at idle, at about 3000 rpm with no load, and under load (RepairPal's suggested three checks). Large negative numbers confirm the rich condition.
Watch the coolant temperature reading on the scan tool. If it stays low on a fully warmed engine, suspect the thermostat or coolant temperature sensor.

Typical fixes

Clean or replace the MAF sensor
Replace a stuck fuel pressure regulator or repair a restricted return line
Clean or replace leaking fuel injectors
Replace a faulty MAP, coolant temperature, intake air temperature or throttle position sensor
Replace a thermostat stuck open
Repair vacuum hoses or the MAP vacuum line
Install a PCM software update if the manufacturer has one
Repair engine mechanical problems such as timing or head gasket faults

Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.

🛠 When to call a pro

Fuel pressure needs to be tested with a gauge, and injector winding resistance or pulse width needs checking (RepairPal)
The engine misfires, runs rough, or the check engine light flashes
You smell raw fuel or see fuel leaking anywhere
The code returns after cleaning the MAF sensor and checking hoses
RepairPal lists oxygen sensors, fuel pumps, fuel injectors and fuel pressure regulators as commonly misdiagnosed for this code, so ask for confirmation before those parts are replaced

Where to buy

Plain search links. Always match parts to your exact year, make, model and engine.

OBD2 scanners on Amazon Parts at Advance Auto Parts catalog at RockAuto

FAQs

Can I drive with P0175?

Sources disagree on how serious it is. RepairPal rates it 'Urgent', while OBD-Codes.com says you probably won't notice drivability problems. Short trips are usually possible if the engine runs normally, but get it diagnosed soon because a rich mixture can cause misfires and damage the catalytic converter.

What's the difference between P0172 and P0175?

They mean the same thing on different sides of the engine. P0172 is system too rich on bank 1 (the side with cylinder 1), and P0175 is bank 2. When both set, the cause is usually something shared by both banks.

Is P0175 caused by a bad oxygen sensor?

Usually not. RepairPal explains that the computer tests the oxygen sensors before it trusts them for fuel trim, so the sensors are usually reporting a real rich condition. It lists oxygen sensors as a common misdiagnosis, though an intermittent heater fault can occasionally contribute.

Can a vacuum leak cause P0175?

OBD-Codes.com lists a vacuum leak as a possible cause. A vacuum leak usually lets in extra unmetered air and causes a lean code instead (such as P0171/P0174), and RepairPal does not list it. A leak in the MAP sensor's vacuum line is different: RepairPal says it can make the computer add fuel and run rich.

How much does it cost to fix P0175?

Neither source gives a repair cost for P0175. The price depends on the cause, from a can of MAF cleaner to a new sensor, regulator or injectors, so get a diagnosis first.

Sources

Last reviewed 2026-10-22. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.