Caterpillar — Combustion Sensor - Clean/Inspect/Replace
Maintenance
From a Caterpillar owner's manual covering: 1YG1-Up, 4CG1-Up, G3612, G3616. Check it applies to your exact model before use.
Applies to: Caterpillar G3612, Caterpillar G3616
Before you start
- Pressurized air can cause personal injury. Wear protective face shield, clothing, and shoes.
Procedure
- Disconnect harness connector (1). Remove O-ring seal. Clean connector. Install new O-ring seal.
- Remove connector (2). Clean connector adapters.
- Remove extension (3). Clean both ends.
- Remove debris around sensor (4) with compressed air (max 207 kPa).
- Loosen sensor (4) with 15.9 mm spark plug socket. Remove by hand.
- Discard gasket (9). Inspect sensor for damage. Discard if terminal post moves, insulator cracked, or shell damaged.
- Measure resistance between terminal post (6) and electrode (10). Must not exceed 5 ohms at 15 VDC.
- Clean sensor shell and electrode using glass beads. Do not use wire brush.
- Install new 108-3515 Plug Gasket. Install sensor by hand. Tighten to 38 ± 2 N·m.
- Install extension (3) aligning discs (5).
- Ensure O-ring seal on connector (2) is good. Install connector.
- Attach harness connector (1) to connector (2).
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Tighten sensor to 38 ± 2 N·m
- Resistance must not exceed 5 ohms at 15 VDC
- Maximum air pressure for cleaning must be below 207 kPa
Source: Caterpillar owner's manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.