P1657

Read the instructions below then start the fault diagnostic procedure.

Symptom: A/C malfunctioning.

P1657

Fault symptoms

•	A/C malfunctioning.

On-Board Diagnostics

Type of diagnosis:

-	Continuous. But interrupted when fault criteria fulfilled and will not restart until next driving cycle.

Enable criteria:

-	Ignition in ON position. A/C request has previously arrived on the bus on some occasion (cars with A/C). Output active.

Fault criteria:

-	Output voltage exceeding 2V for more than 1 s.

Dependents:

-

None.

System reaction to a fault:

-	Air mass control A/C compensation blocked.

OK report:

-	Enable criteria fulfilled. A/C (Bus from DICE) is ON and fault criteria not fulfilled within 1.5 s.

Fault handling: (For more information, see .)

-	Type III. CHECK ENGINE does not go on.

Diagnostic help

Fault diagnosis concerns electrical fault in connecting leads or in the relay.

Functions in the diagnostic tool related to the fault:

•	Activate A/C relay output.

For more information, see .

Checking the wiring

Jiggle the wiring harness at several points and in different directions to detect intermittent breaks and short circuits. Observe the multimeter, diagnostic tool or test lamp during the check.