Upper Limit

Checking Throttle Body
- Ignition off.
- Check that seal on throttle body (TB) adjusting screw is not broken.
- Is seal broken?

No:
^ Proceed to test step below.

Yes:
^ Replace throttle body.
^ Then proceed to Verification section below.





Checking The Air Cleaner And Air Intake
- Ignition off.
- Check that the air cleaner (ACL), air intake and hoses and pipes between the air cleaner and throttle body are not blocked. Check the connectors for the idle air control (IAC) valve.

If reading is OK:
^ Proceed to test step below.

If reading is incorrect:
^ Remedy as necessary.
^ Then proceed to Verification section below.





Checking Idle Air Control Valve
- Ignition off.
- Disconnect idle air control valve.
- Connect an ohmmeter between idle air control valve terminals 1 and 3.
- The ohmmeter should read 18 - 28 ohms at +20°C

If reading is OK:
^ Proceed to test step below.

If reading is incorrect:
^ Try a new idle air control valve.
^ Then proceed to Verification section below.





Checking The Idle Air Control Valve Control Slide
- Ignition off.
- Remove the idle air control valve.
- Hold the valve by the connector, twist the valve rapidly but carefully back and forth. Listen for the sound of the slide making switching.

CAUTION: The slide must under no circumstances be touched by a screwdriver or other instrument, since this may scratch and damage the slide.

- The idle air control valve control slide should switch.

If reading is OK:
^ Check the idle air control valve and engine control module (ECM) connectors for contact resistance and oxidation.
^ Then proceed to Verification section below.

If reading is incorrect:
^ Try a new idle air control valve.
^ Then proceed to Verification section below.





Verification
- After carrying out the repair, check that the fault has been remedied as follows.
- Ignition on.
- Throttle position sensor and engine control module connected.
- Ignition on.
- Erase all adaptive functions but the flywheel.
- Start the engine and run it until it reaches operating temperature, at least 85°C.
- Engine idling.
- Read off idle air trim adaption.
- When the idle air trim adaption value has stabilized. Rev the engine to approx. 2,000 and idle it.
- Wait approx. 30 seconds and read off the value again. Repeat this until the value is stable.
- The value should be between -5 and +15 kg/h.

If reading is OK:
^ Fault corrected

If reading is incorrect:
^ Proceed to test step below.

DTC Information
The verification result shows that the fault persists.

- Do you want to exit fault-tracing?

Yes:
^ Fault not corrected

No:
^ Return to Checking Throttle Body section above.