Fuel Trim (Bank 2)

What it means

This code appears on engines with two banks and means that fuel trim on the bank without cylinder 1 has reached its limit or stayed out of range, without saying whether the mixture is lean or rich. Comparing bank 2 with bank 1 is the key step to find out whether the cause is on that side or shared.

Related codes: P0174P0175P0170P0150P0101

Symptoms4

• Check engine light on.
• Uneven idle.
• Slight hesitation or weak acceleration.
• Change in fuel consumption.

Possible causes5

• Air leak at the intake manifold gasket on the bank 2 side or from a nearby vacuum hose.
• Clogged or leaking injector on bank 2.
• Faulty bank 2 upstream oxygen sensor.
• Leak in the bank 2 exhaust manifold ahead of the sensor.
• A shared cause such as the MAF sensor or fuel pressure, especially if bank 1 has a similar code.

How to diagnose5

1. Read fuel trims for both banks; if only bank 2 is out of range, the cause is on that side.
2. Find the direction: large positive values mean lean, large negative values mean rich.
3. Have a smoke test done, focusing on the bank 2 side of the intake manifold.
4. Check the bank 2 upstream oxygen sensor and compare its signal with bank 1.
5. Check the bank 2 injectors and how evenly they deliver fuel.

How to fix5

1. Repair the air leak or replace the intake manifold gasket.
2. Repair any exhaust leak ahead of the bank 2 oxygen sensor.
3. Replace the bank 2 upstream oxygen sensor if it is proven faulty.
4. Clean the bank 2 injectors or replace a faulty one.
5. Clear the codes and confirm both banks show similar, normal fuel trims.

Repair cost

In Saudi riyals; the highlighted part is the expected range for this fault.

A simple air leak costs little; the cost rises when the intake manifold gasket or injectors must be replaced.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions