System Readiness Test (SRT) Code: Notes
System Readiness Test (SRT) code is specified in Service $01 of SAE J1979.
As part of an enhanced emissions test for Inspection & Maintenance (I/M), certain states require the status of SRT be used to indicate whether the ECM has completed self-diagnosis of major emission systems and components. Completion must be verified in order for the emissions inspection to proceed.
If a vehicle is rejected for a State emissions inspection due to one or more SRT items indicating "INCMP", use the information in this article to set the SRT to "CMPLT".
In most cases the ECM will automatically complete its self-diagnosis cycle during normal usage, and the SRT status will indicate "CMPLT" for each application system. Once set as "CMPLT", the SRT status remains "CMPLT" until the self-diagnosis memory is erased.
Occasionally, certain portions of the self-diagnostic test may not be completed as a result of the customer's normal driving pattern; the SRT will indicate "INCMP" for these items.
If, during the state emissions inspection, the SRT indicates "CMPLT" for all test items, the inspector will continue with the emissions test. However, if the SRT indicates "INCMP" for one or more of the SRT items the vehicle is returned to the customer untested.
SRT Item
The table below shows required self-diagnostic items to set the SRT to "CMPLT".
| SRT item (CONSULT-III indication) | Performance Priority(1) | Required self-diagnostic items to set the SRT to "CMPLT" | Corresponding DTC No. | ||
|---|---|---|---|---|---|
| CATALYST | 2 | Three way catalyst function | P0420, P0430 | ||
| EVAP SYSTEM | 2 | EVAP control system purge flow monitoring | P0441 | ||
| 1 | EVAP control system | P0442 | |||
| 2 | EVAP control system | P0456 | |||
| HO2S | 2 | Air fuel ratio (A/F) sensor 1 | P0133, P0153 | ||
| Heated oxygen sensor 2 | P0137, P0157 | ||||
| Heated oxygen sensor 2 | P0138, P0158 | ||||
| Heated oxygen sensor 2 | P0139, P0159 | ||||
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SRT Set Timing
SRT is set as "CMPLT" after self-diagnosis has been performed one or more times. Completion of SRT is done regardless of whether the result is OK or NG. The set timing is different between OK and NG results and is shown in the table below.
| Self-diagnosis result | Example | |||||
|---|---|---|---|---|---|---|
| Diagnosis | Ignition cycle ← ON → OFF ← ON → OFF ← ON → OFF ← ON → | |||||
| All OK | Case 1 | P0400 | OK (1) | -- (1) | OK (2) | -- (2) |
| P0402 | OK (1) | -- (1) | -- (1) | OK (2) | ||
| P1402 | OK (1) | OK (2) | -- (2) | -- (2) | ||
| SRT of EGR | "CMPLT" | "CMPLT" | "CMPLT" | "CMPLT" | ||
| Case 2 | P0400 | OK (1) | -- (1) | -- (1) | -- (1) | |
| P0402 | -- (0) | -- (0) | OK (1) | -- (1) | ||
| P1402 | OK (1) | OK (2) | -- (2) | -- (2) | ||
| SRT of EGR | "INCMP" | "INCMP" | "CMPLT" | "CMPLT" | ||
| NG exists | Case 3 | P0400 | OK | OK | - | - |
| P0402 | - | - | - | - | ||
| P1402 | NG | - | NG | NG (Consecutive NG) | ||
| (1st trip) DTC | 1st trip DTC | - | 1st trip DTC | DTC (= MIL ON) | ||
| SRT of EGR | "INCMP" | "INCMP" | "INCMP" | "CMPLT" | ||
| OK: Self-diagnosis is carried out and the result is OK. NG: Self-diagnosis is carried out and the result is NG. -: Self-diagnosis is not carried out. |
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When all SRT related self-diagnoses showed OK results in a single cycle (Ignition OFF-ON-OFF), the SRT will indicate "CMPLT". → Case 1 above
When all SRT related self-diagnoses showed OK results through several different cycles, the SRT will indicate "CMPLT" at the time the respective self-diagnoses have at least one OK result. → Case 2 above
If one or more SRT related self-diagnoses showed NG results in 2 consecutive cycles, the SRT will also indicate "CMPLT". → Case 3 above
The table above shows that the minimum number of cycles for setting SRT as "INCMP" is one (1) for each self-diagnosis (Case 1 & 2) or two (2) for one of self-diagnoses (Case 3). However, in preparation for the state emissions inspection, it is unnecessary for each self-diagnosis to be executed twice (Case 3) for the following reasons:
- The SRT will indicate "CMPLT" at the time the respective self-diagnoses have one (1) OK result.
- The emissions inspection requires "CMPLT" of the SRT only with OK self-diagnosis results.
- When, during SRT driving pattern, 1st trip DTC (NG) is detected prior to "CMPLT" of SRT, the self-diagnosis memory must be erased from ECM after repair.
- If the 1st trip DTC is erased, all the SRT will indicate "INCMP".NOTE: SRT can be set as "CMPLT" together with the DTC(s). Therefore, DTC check must always be carried out prior to the state emission inspection even though the SRT indicates "CMPLT".
SRT Service Procedure
If a vehicle has failed the state emissions inspection due to one or more SRT items indicating "INCMP", review the flowchart diagnostic sequence on the next page.