Code 34
Code 34 is a diagnostic trouble code related to the Manifold absolute pressure sensor circuit on the Pontiac Fiero.
Code 34 indicates that the ECM has detected a manifold absolute pressure sensor signal that represents unusually high vacuum or low manifold pressure.
Overview
The manifold absolute pressure sensor, often abbreviated as MAP sensor, tells the ECM how much pressure or vacuum is present in the intake manifold.
The ECM uses this signal for fuel mixture, ignition timing, load calculation, and drivability control.
Code 34 is set when the ECM detects a MAP sensor problem with an unusual high-vacuum or low-pressure reading. Common checks include the MAP sensor vacuum hose, sensor connector, wiring, and the MAP sensor itself.
Flash pattern
Code 34 is displayed as:
- Three flashes
- Pause
- Four flashes
This represents code 34.
Animated flash pattern:
Meaning
Code 34 usually indicates that the ECM is seeing the MAP sensor signal as too low, corresponding to high intake vacuum or low manifold pressure.
Possible causes include:
- Faulty MAP sensor
- MAP sensor wiring problem
- Poor connector contact
- Open or shorted MAP sensor circuit
- Blocked MAP sensor vacuum hose
- Incorrect MAP sensor vacuum signal
- ECM input problem
Symptoms
Possible symptoms may include:
- Check engine light
- Poor acceleration
- Hesitation
- Stalling
- Rough idle
- Poor fuel economy
- Lean or rich running depending on conditions
- Poor drivability
- Little or no obvious drivability problem
Diagnosis
Basic diagnostic checks include:
- Confirm that Code 34 is present.
- Inspect the vacuum hose from the intake manifold to the MAP sensor.
- Check for a blocked, damaged, disconnected, or leaking MAP vacuum hose.
- Inspect the MAP sensor connector.
- Inspect MAP sensor wiring for damage.
- Check for poor connector contact or corrosion.
- Check for other stored trouble codes.
- Test the MAP sensor signal if equipment is available.
- Check ECM connector condition if the sensor, vacuum hose, and wiring appear correct.
Vacuum hose
The MAP sensor must receive a correct manifold pressure signal through its vacuum hose. A damaged, blocked, disconnected, or incorrectly routed hose can cause the ECM to see an incorrect load signal.
Related topics:
Related codes
Related MAP sensor codes include:
- Code 33 - MAP sensor circuit, high voltage or unusually low vacuum/high pressure indication
Notes
Code 34 should not automatically be treated as a failed MAP sensor. The vacuum hose, electrical connector, wiring, engine vacuum condition, and ECM input should also be checked.
If the MAP sensor signal is incorrect, the ECM may calculate engine load incorrectly, which can cause significant drivability problems.