Notes On Trouble Codes

When certain trouble codes occur, MIL on instrument panel will not come on. For designation of MIL operation on certain trouble codes, see appropriate TROUBLE CODE IDENTIFICATION table under TROUBLE CODE IDENTIFICATION.
When certain malfunctions or trouble codes initially occur, they will be temporarily stored in ECM memory, but MIL on instrument panel will not come on.

The second time malfunction or trouble code is detected, MIL on instrument panel will then come on, provided ignition is turned off and then back on after malfunction or trouble code was first detected. This is referred to as the Two Trip Detection Logic and only applies to specified trouble codes. See TWO TRIP DETECTION LOGIC TROUBLE CODES table.

NOTE: When road testing vehicle in Test Mode, the Two Trip Detection Logic will not function. In Test Mode, the MIL on instrument panel will come on the first time malfunction or trouble code is detected.

TWO TRIP DETECTION LOGIC TROUBLE CODES

Application

⁽¹⁾ Trouble Code

Corolla

21, 25, 26, 27 & 71

⁽¹⁾	Trouble codes may not apply to all models, as some trouble codes are used only on Calif. models.

In Normal Mode, MIL on instrument panel will go off after malfunction is repaired, but trouble codes, except ECM non-memory trouble codes, will be retained in ECM memory until cleared. ECM non-memory trouble codes are not stored in ECM memory. See ECM NON-MEMORY TROUBLE CODES table.
In Test Mode, all trouble codes except ECM non-memory trouble codes are retained in ECM memory, even with ignition off and repairs made, until cleared. ECM non-memory trouble codes are not retained in ECM memory. See ECM NON-MEMORY TROUBLE CODES table.

NOTE: When in Test Mode, if vehicle is not driven at a speed greater than 6 MPH, ECM will set Trouble Codes 42 and 43. For MIL operation in relation to trouble code when in Test Mode, see appropriate TROUBLE CODE IDENTIFICATION table under TROUBLE CODE IDENTIFICATION.

ECM NON-MEMORY TROUBLE CODES

Application		Trouble Code
Normal Mode
1.6L (4A-FE)		43 & 51
1.8L (7A-FE))		16, 43 & 51
Test Mode		43 & 51