P0172 (blink 26) on Toyota Corolla E120: SYSTEM TOO RICH(FUEL TRIM)

Short answer: P0172 means “SYSTEM TOO RICH(FUEL TRIM)”. The car’s computer has found a fault in the EFI 1NZ-FE/2NZ-FE system and turns on the Malfunction indicator lamp (Check Engine). First check: workshop check order (RM821E): CHECK EMISSION CONTROL SYSTEM -> CHECK FUEL INJECTOR ASSY -> CHECK WATER TEMPERATURE SENSOR -> CHECK FOR SPARK AND IGNITION -> CHECK FUEL PRESSURE -> CHECK EXHAUST GAS LEAKAGE POINT -> READ VALUE OF O2S B1,S1 -> CHECK HARNESS AND CONNECTOR(ENGINE ECU−OXYGEN SENSOR) (See -> PERFORM CONFIRMATION DRIVING PATTERN -> READ OUTPUT DTC CODES.

Code

P0172 · blink 26

System

EFI 1NZ-FE/2NZ-FE

Dashboard light

Malfunction indicator lamp (Check Engine)

Applies to

2NZ-FE 1.3 (PK XLi/GLi NZE120) and 1NZ-FE 1.5 (JDM NZE121/NZE124 Corolla/Fielder/Runx)

Market note

HONG KONG ONLY

Confidence

high (official Toyota RM821E)

Source

toyotamanuals.gitlab.io

Symptoms and when it is set

1. Oxygen sensor voltage is 0.45 V or less (lean) for 90 sec. under conditions (a), (b) and (c): (2 trip detection logic) (a) Water temp.: 70˚C (158˚F) or more (b) Engine speed: 1,500 rpm or more (c) Vehicle speed: 100 km/h (62 mph) or less

Likely causes

1. Air intake (hose loose); Fuel line pressure; Open or short in oxygen sensor circuit; Oxygen sensor malfunction; Air flow meter; Water temp. sensor; Gas leakage on exhaust system

What to check, in order

1. Workshop check order (RM821E): CHECK EMISSION CONTROL SYSTEM -> CHECK FUEL INJECTOR ASSY -> CHECK WATER TEMPERATURE SENSOR -> CHECK FOR SPARK AND IGNITION -> CHECK FUEL PRESSURE -> CHECK EXHAUST GAS LEAKAGE POINT -> READ VALUE OF O2S B1,S1 -> CHECK HARNESS AND CONNECTOR(ENGINE ECU−OXYGEN SENSOR) (See -> PERFORM CONFIRMATION DRIVING PATTERN -> READ OUTPUT DTC CODES

Related on this car

• Poor fuel average after a bad tune-up
• All fault codes for this car
• Warning lights
• Where the parts are (parts map)
• Common problems

Same code on other cars

• P0172 · Toyota Passo (1st gen)
• P0172 · Toyota Corolla (11th gen, E170)
• P0172 · Toyota Corolla (10th gen, E140)
• P0172 · Honda City (5th gen, GM2)
• P0172 · Honda Civic (10th gen, FC)
• P0172 · Suzuki Wagon R (Pakistan, K10B)
• P0172 on all cars compared

← P0171/25 P0325/52 →

Clearing the code does not fix the fault. If it comes back, the problem is still there. For brakes, airbags and steering, see a trained mechanic.