Cliff: Created page with "'''Code 35''' is a diagnostic trouble code related to idle speed control on the Pontiac Fiero. Code 35 indicates that the ECM cannot maintain the expected idle speed. == Overview == The ECM controls idle speed by adjusting the amount of air bypassing the throttle plate. On Fieros equipped with an idle air control system, this is handled through the Idle air control valve, often abbreviated as IAC. Code 35 is set when the actua..."

2026-07-06T19:01:29Z

Created page with "'''Code 35''' is a diagnostic trouble code related to idle speed control on the Pontiac Fiero. Code 35 indicates that the ECM cannot maintain the expected idle speed. == Overview == The ECM controls idle speed by adjusting the amount of air bypassing the throttle plate. On Fieros equipped with an idle air control system, this is handled through the Idle air control valve, often abbreviated as IAC. Code 35 is set when the actua..."

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'''Code 35''' is a [[Diagnostic trouble codes|diagnostic trouble code]] related to idle speed control on the [[Pontiac Fiero]].

Code 35 indicates that the [[ECM]] cannot maintain the expected idle speed.

== Overview ==

The ECM controls idle speed by adjusting the amount of air bypassing the throttle plate. On Fieros equipped with an idle air control system, this is handled through the [[Idle air control valve]], often abbreviated as IAC.

Code 35 is set when the actual idle speed is outside the expected range for a certain period of time.

A Code 35 does not automatically mean the idle air control valve is bad. Idle speed errors may also be caused by vacuum leaks, throttle body problems, incorrect minimum air setting, sticking throttle linkage, wiring problems, sensor problems, or engine mechanical issues.

== Flash pattern ==

Code 35 is displayed as:

* Three flashes
* Pause
* Five flashes

This represents code '''35'''.

'''Animated flash pattern:'''

[[File:Code35.gif|none]]

== Meaning ==

Code 35 usually indicates that the ECM is unable to control idle speed correctly.

Possible causes include:

* Vacuum leak
* Dirty throttle body
* Faulty idle air control valve
* IAC wiring problem
* Poor IAC connector contact
* Incorrect idle adjustment
* Sticking throttle linkage
* Throttle plate not closing correctly
* Misadjusted [[Throttle position sensor]]
* EGR leak
* Poor engine grounds
* ECM control problem

== Symptoms ==

Possible symptoms may include:

* Check engine light
* High idle
* Low idle
* Surging idle
* Rough idle
* Stalling
* Idle speed changes unexpectedly
* Idle does not settle after throttle is released
* Idle problems when coming to a stop

== Diagnosis ==

Basic diagnostic checks include:

# Confirm that Code 35 is present.
# Check for [[Vacuum leaks]].
# Inspect the throttle body for dirt or carbon buildup.
# Check that the throttle linkage moves freely.
# Check that the throttle plate returns fully.
# Inspect the idle air control valve connector and wiring.
# Check the idle air control valve if appropriate.
# Check the throttle position sensor signal and adjustment if applicable.
# Check for EGR leakage.
# Check for other stored trouble codes.
# Check grounds and ECM connections if the basic checks do not identify the problem.

== Vacuum leaks ==

Vacuum leaks are a common cause of idle problems. A vacuum leak can allow unmetered air into the engine, causing idle speed to rise or become unstable.

Related topics:

* [[Vacuum leaks]]
* [[EGR tube]]
* [[EGR valve]]
* [[MAP sensor]]
* [[Throttle body]]

== Idle air control valve ==

The idle air control valve allows the ECM to adjust idle air flow. If the valve sticks, fails, or cannot move as commanded, idle speed may be too high, too low, or unstable.

Related topics:

* [[Idle air control valve]]
* [[Throttle body]]
* [[Idle problems]]
* [[ECM]]

== Related codes ==

Related idle and throttle codes include:

* [[Code 21]] - Throttle position sensor circuit, high voltage
* [[Code 22]] - Throttle position sensor circuit, low voltage
* [[Code 33]] - MAP sensor circuit, high voltage
* [[Code 34]] - MAP sensor circuit, low voltage

== Notes ==

Code 35 should be diagnosed as an idle-control problem, not as an automatic idle air control valve replacement.

The ECM may be trying to correct an idle problem caused by a vacuum leak, throttle-body issue, EGR leak, sensor problem, or mechanical issue.

== See also ==

* [[Diagnostic trouble codes]]
* [[ALDL diagnostics]]
* [[Idle problems]]
* [[Idle air control valve]]
* [[Throttle body]]
* [[Vacuum leaks]]
* [[Throttle position sensor]]
* [[ECM]]
* [[Code 21]]
* [[Code 22]]

[[Category:Fieropedia]]
[[Category:Diagnostics]]
[[Category:Electrical system]]
[[Category:Engine]]

Code 35 - Revision history