E033

Code E033 - Mass Air Flow Sensor (Signal Frequency High):

Wiring Diagram for Code E033 - Mass Air Flow Sensor (Signal Frequency High):

CODE E033 - MASS AIR FLOW SENSOR (SIGNAL FREQUENCY HIGH)

Circuit Description:

The Mass Air Flow (MAF) sensor measures the amount of air which passes through it in a given time. The ECM uses this information to monitor the operating condition of the engine, in calculating fuel delivery. A large quantity of air movement indicates acceleration, while a small quantity indicates deceleration or idle.

The MAF sensor produces a frequency signal which cannot be easily measured. The sensor can be diagnosed using the procedures on this chart and with the aid of MAF sensor tester.

Code E033 will set when the following conditions are met:

a. E021 or E022 not present
b. Engine is running at less than 800 RPM
c. TPS is less than 500mv
d. Air Flow more than 150 grams per second
e. All of the above are met for 5 seconds or more




Test Description: The following numbered steps correspond with the step numbers on the diagnostic chart.

1. At normal idle speed on a warm engine, ECM Data ED21 (MAF) should display less than 25 Grams Per Second (GPS). A display higher than that would indicate a faulty sensor.

2. Inspect wire routing of high voltage wires, such as spark plug wires. Such wires routed too closely to MAF wiring harness could possibly cause an intermittent Code E033.




Diagnostic Aids:

An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation.

Check For:

a. Poor Connection or Damaged Harness - Inspect ECM harness connectors for backed out terminal "B6", improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.

b. Intermittent Test - If connections and harness checks out ok, monitor ED21 (MAF) display while moving related connectors and wiring harness. If the failure is induced, the "MAF" display will abruptly change. This will help to isolate the location of the malfunction.

c. Misrouted Harness - Inspect MAF sensor harness to insure that it is not too close to high voltage wires, such as spark plug leads.

d. Miscalibrated MAF Sensor - The Mass Air Flow Sensor may be tested for being out of specification by using a MAF Sensor test tool.