More Information for APWI AP128
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APWI Oxygen Sensor Features:

Sensor element is made with highly pure and concentrated platinum paste imported from Germany. This will result in increased sensor life.

Supplied with high temperature nickel plated Teflon wire with Dupont material. Wires protected with fiberglass protective sleeve.

Made with Viton Flourine rubber boots. Viton is water resistant and will decrease oil steam and vapor residue.

Sensor Body
• Made with high temperature stainless steel for long sensor life.

Frontal Tube
• Double layered with high quality stainless steel imported from Germany. Increases life expentancy of the sensor.

• OE direct fit connectors. No consolidations.

Hex Nut
• Improved Hex nut design for easier grip and installation.

NOTE: Part number prefix will tell you how many wires each sensor has.
AP1 = 1 Wire
AP2 = 2 Wires
AP3 = 3 Wires
AP4 = 4 Wires
AP5 = 5 Wires
O2 Sensor Identification Guide

An OBD Scan Tool will usually identify Oxygen Sensors by the Bank Number (B1 = Bank 1) and Sensor Number (S1 = Sensor 1). Bank 1 will always contain Cylinder 1, which is located closest to the front of the engine.

Part manufacturers often use different terms than scan tools to identify sensor positions. Regardless of the vehicle's engine orientation, the right or left bank is determined by viewing the engine from the rear (opposite the drive belts).

Upstream Sensor (Before Converter)
Downstream Sensor (After Converter)
Left or Front Upstream Sensor (Before Converter)
Right or Rear Upstream Sensor (Before Converter)

Engine Bank Identification
Common O2 Sensor Contaminants

Oxygen (O2) Sensors commonly fail due to contamination. When checking or replacing an O2 Sensor, visually inspect the sensor body to determine if it has been contaminated by a faulty part or substance upstream, and correct the fault before replacing the sensor.

Common Causes:
  • Cracked or warped cylinder head
  • Leaking cylinder head gasket
  • Leaking intake manifold gasket
Antifreeze Poisoned O2 Sensor
Antifreeze Poisoned O2 Sensor
Common Causes:
  • Use of an improper silicone gasket sealant on the engine

Silicone Poisoned O2 Sensor
Silicone Poisoned O2 Sensor
Common Causes:
  • Clogged air filter
  • Leaking or defective fuel injector

Carbon Buildup O2 Sensor
Carbon Buildup O2 Sensor
Alternate/OEM Part Number(s): AP1-28

APWI Warranty Information:
12 months/12,000 miles