P1604

Read the instructions below then start the fault diagnostic procedure.

Symptom: CHECK ENGINE. Incorrect idling speed. Cruise control not working.

P1604

Fault symptoms

•	CHECK ENGINE.

•	Incorrect idling speed.

•	Cruise control not working.

On-Board Diagnostics

Type of diagnosis:

-	Continuous. However, it is interrupted once the fault criteria have been fulfilled and does not restart until the next driving cycle.

Enable criteria: (Conditions that must be fulfilled for diagnostics to be performed.)

-	Ignition in position ON.

Fault criteria: (When enable criteria have been fulfilled, diagnostics will check if the fault criteria have been fulfilled.)

-	ROM malfunction in processor 339.

Dependents: (Once fault criteria have been fulfilled, a number of other diagnostics must report OK before the diagnostic trouble code can finally be generated.)

-

None.

System reaction to a fault: (Once the fault criteria have been fulfilled, certain measures will sometimes be taken.)

-	Throttle control put into limp-home mode. The limp-home solenoid will activate 5 times in succession each time the ignition is turned on until the fault is rectified and the diagnostic trouble codes are cleared.

OK report: (This diagnosis may be included as a dependent to another diagnosis and must therefore report OK even if it is continuous. The OK report is also used in fault handling to count down the fault counter.)

-	Accelerator depressed on some occasion and then released fully. 120s has passed since then without the fault criteria being fulfilled.

Fault handling: (Refer to section “Fault diagnosis, general” for more information.)

-	CHECK ENGINE goes on directly and can be turned off only by clearing the diagnostic trouble codes.

Diagnostic help

Fault diagnosis concerns an internal control module malfunction.

See .