DTC P0170 (Fuel): Fuel Trim Malfunction

Check for the following items in exhaust system:
- Looseness of installation components
- Damage to parts (cracks, holes, etc.)
- Looseness or opening of parts between front and rear O2S
Replace or repair defective parts. If no defects, go to next step.
Check for the following items in air intake system:
- Looseness of installation components
- Damage to parts (cracks, holes, etc.)
- Disconnection of hose on air intake system
Replace or repair defective parts. If no defects, go to next step.

WARNING: Release fuel pressure before removing fuel lines.
Remove fuel pump access cover located a right rear of trunk (sedan) or luggage compartment floor (wagon). Disconnect connector from fuel tank. Start and operate engine until it stalls. After engine stalls, crank engine for 5-7 seconds to ensure reduced fuel pressure.
NOTE: During test, if fuel pressure does not increase, squeeze fuel return hose 2-3 times and recheck fuel pressure.

Turn ignition off. Reconnect fuel tank connector. Disconnect fuel delivery hose from fuel filter and connect a fuel pressure gauge between filter and delivery hose. Start engine and idle with transmission in Park or Neutral. Check fuel pressure with pressure regulator hose disconnected from intake manifold. See the FUEL PRESSURE SPECIFICATIONS table. If fuel pressure is within specifications, go to next step. If fuel pressure is too high, check for clogged fuel return line or bent hose. If fuel pressure is too low, check for improper fuel pump discharge or clogged fuel supply line.

FUEL PRESSURE SPECIFICATIONS

Vacuum Line ⁽¹⁾

psi (kg/cm² )

Connected

23-30 (1.6-2.1)

Disconnected

33-40 (2.3-2.8)

⁽¹⁾	Connected or disconnected to fuel pressure regulator.

Check fuel pressure with pressure regulator vacuum hose connected. See FUEL PRESSURE SPECIFICATIONS table. If fuel pressure is within specifications, go to next step. If fuel pressure is too high, check for faulty pressure regulator, clogged fuel return line or bent hose. If fuel pressure is too low, check for faulty pressure regulator, improper fuel pump discharge or clogged fuel supply line.
WARNING: Release fuel pressure before removing fuel pressure test gauge. See step 3).
Remove fuel pressure test gauge. Start engine. Check for leaks. Turn ignition off. Connect SSM. Start and warm engine to normal operating temperature. Set SSM to function mode F04 to read coolant temperature. If temperature reading is more than 140°F (60°C), go to next step. If temperature reading is less than 140°F (60°C), replace Engine Coolant Temperature (ECT) sensor.
Ensure all accessories are off. Set SSM to function mode F06 to show mass airflow and voltage input from MAF sensor. See the MASS AIRFLOW SENSOR VALUES table. If the mass airflow is not as specified, replace MAF sensor. If mass airflow is as specified, substitute with a known-good ECM and retest system.

MASS AIRFLOW SENSOR VALUES

Engine Speed

Specified Value (g/sec)

1.8L

Idling

1.6-2.8

2500 RPM

6.1-10.3

2.2L

Idling

1.7-3.3

2500 RPM

7.1-14.2

2.5L

⁽¹⁾

⁽¹⁾	Information not available.