| Parameter | Details |
|---|---|
| Product Name | Engine Coolant Temperature Sensor / Intake Air Temperature Sensor |
| Part Numbers | 128-8945, 342-2924 ，4I-5394 |
| Compatible Brands | Caterpillar (CAT) |
| Compatible Machine Model | CAT 325C |
| Compatible Engine | CAT C9 (9.3L, 6-cylinder, ACERT) |
| Sensor Type | Temperature Sensor (Thermistor / RTD type) |
| Material | Brass / Stainless Steel + Rubber Seals |
| Packing | PP bag inside, carton box outside |
| Payment Terms | Western Union, L/C, T/T, MoneyGram, D/A, D/P |
| MOQ | Acceptable trial order (1 piece accepted) |
| Shipping Mode | Air/Sea/Express (FedEx, UPS, DHL, TNT, etc.) |
| Place of Origin | Guangdong, China |
| Brand Name | COGENG |
| Certification | ISO9001 |
| Stock Status | ✅ In Stock |
| Supply Capacity | 500 PCS |
The COGENG 128-8945 / 342-2924 Temperature Sensor is a high-precision, direct OEM replacement sensor specifically designed for Caterpillar 325C excavators powered by the CAT C9 engine.
This sensor serves as either an:
Engine Coolant Temperature (ECT) Sensor – Monitors engine coolant temperature for ECM fuel control and dash gauge.
Intake Air Temperature (IAT) Sensor – Monitors turbocharged air temperature for ECM fueling and timing adjustments.
Fuel Temperature Sensor – Monitors fuel temperature for injection timing compensation.
Depending on the specific location in the engine, the sensor sends a variable resistance signal to the ECM, which uses this data to:
Adjust fuel injection timing and duration.
Control cooling fan operation.
Trigger warning lights if temperatures exceed safe limits.
Enable cold-start assistance when temperatures are low.
Manufactured under ISO9001 certified processes, the COGENG temperature sensor features a brass/stainless steel housing, premium rubber O-ring, and precision thermistor element to ensure accurate readings across a wide temperature range (-40°C to +150°C).
Why Choose COGENG 128-8945 / 342-2924?
Dual Part Number Coverage: 128-8945 and 342-2924 are often used interchangeably on the CAT C9 engine. We supply the correct version based on your specific sensor location.
High Accuracy: Precisely calibrated to CAT C9 ECM specifications.
Direct Fit: Plug-and-play – no adapters required.
In Stock: Ready for immediate shipment.
| Component | Quantity | Description |
|---|---|---|
| Temperature Sensor | 1 | Complete sensor assembly with pre-attached connector |
| Rubber O-ring / Sealing Ring | 1 | Pre-installed on threaded base |
| Protective Plastic Cap | 1 | For shipping protection only |
| Installation Quick Guide | 1 | Basic instructions |
How a Thermistor Temperature Sensor Works:
NTC Thermistor: As temperature increases, resistance decreases.
Signal: The ECM sends a 5V reference voltage through the sensor and measures the return voltage to calculate temperature.
| Temperature | Resistance (Typical) | Voltage Output (Typical) |
|---|---|---|
| -40°C (-40°F) | ~100,000 Ω | ~4.8V |
| 0°C (32°F) | ~30,000 Ω | ~3.8V |
| 25°C (77°F) | ~10,000 Ω | ~2.8V |
| 80°C (176°F) | ~2,000 Ω | ~1.5V |
| 120°C (248°F) | ~500 Ω | ~0.5V |
| Machine Model | Engine | Compatible Sensor | Location |
|---|---|---|---|
| CAT 325C | C9 ACERT | 128-8945 | Coolant / Intake Air |
| CAT 325C | C9 ACERT | 342-2924 | Coolant / Intake Air / Fuel |
| 4I-5394 | Associated Part Number | ||
| CAT 325D | *C7 / C7.1* | Not compatible | Different sensor connector |
| CAT 330C | C9 | Check | May fit – verify |
| CAT 320C | *3066* | Not compatible | Different sensor |
⚠️ Important: Both 128-8945 and 342-2924 are used on the CAT C9 engine. The difference is typically the connector type or thread size. Always check your old sensor.
✅ Direct OEM replacement for:
CAT Part Number: 128-8945
CAT Part Number: 342-2924
✅ Designed For:
CAT 325C excavator
CAT C9 ACERT engine
Engine coolant temperature monitoring
Intake air temperature monitoring
Fuel temperature monitoring
✅ Electrical Specifications:
Connector: 2-pin Deutsch (standard)
Voltage: 5V DC reference (from ECM)
Output: Variable resistance (NTC thermistor)
✅ Mechanical Specifications:
Thread Size: 1/8-27 NPT or M10x1
Hex Size: 17mm, 19mm, or 22mm
Sealing: Rubber O-ring (pre-installed)
⚠️ Before purchasing, please verify:
| Check Item | Details |
|---|---|
| Machine Model | CAT 325C (not 325D, 325B, or 325C L – check) |
| Engine Type | CAT C9 ACERT (9.3L) |
| Sensor Location | Coolant, Intake Air, or Fuel |
| Connector Type | 2-pin Deutsch |
| Thread Size | 1/8-27 NPT or M10x1 |
❌ NOT Compatible With:
CAT 325C with 3066 engine (older model).
CAT 325D – uses different sensor part numbers.
CAT C7 or C7.1 engines.
Non-CAT engines (different ECM calibration).
Step 1: Preparation
Turn off engine and allow it to cool completely (coolant/fuel can be hot).
Disconnect batteries (negative first).
Step 2: Locate the Old Sensor
Coolant Sensor: Typically located on the thermostat housing or cylinder head.
Intake Air Sensor: Located in the intake manifold or charge air cooler pipe.
Fuel Temperature Sensor: Located on the fuel filter base or fuel rail.
Step 3: Remove the Old Sensor
Disconnect the electrical connector (press locking tab).
Use the appropriate wrench (17mm, 19mm, or 22mm) – counter-clockwise.
Place a rag underneath to catch any fluid drips.
Step 4: Install the New Sensor
Check the rubber O-ring is in place.
Apply a small amount of clean engine oil or coolant to the O-ring.
Hand-tighten the sensor into the port.
Torque to specification: 15–25 Nm (11–18 ft-lbs) – do not overtighten.
Reconnect the electrical connector (click = secure).
Step 5: Test
Reconnect batteries.
Start engine and check for leaks.
Use CAT ET (Electronic Technician) to verify temperature readings.
Allow engine to reach operating temperature and confirm gauge/monitor reads correctly.
Q1: What is the difference between 128-8945 and 342-2924?
A: Both are temperature sensors for the CAT C9 engine. The difference is typically:
128-8945: Often used for coolant temperature.
342-2924: Often used for intake air temperature or fuel temperature.
They may have slightly different resistance curves or connector types. Always match your old sensor.
Q2: What are the symptoms of a failing temperature sensor on a CAT 325C?
A: Common symptoms include:
Check Engine Light (CEL) with codes related to temperature sensors.
Engine derates (reduced power) due to incorrect ECM readings.
Hard starting in cold weather.
Incorrect gauge reading (stays at 0 or pegged at maximum).
Cooling fan running constantly or not running at all.
Poor fuel economy.
Q3: Is this a genuine CAT part?
A: No. COGENG is an aftermarket manufacturer (ISO9001) . Our parts are built to OEM specifications.
Q4: Which sensor do I need – 128-8945 or 342-2924?
A: Check your old sensor for the part number stamp on the housing. If it's not visible, note:
Location: Coolant sensor vs intake air sensor.
Connector: They may differ.
Send a photo of your old sensor to your COGENG distributor for confirmation.
Q5: Do I need CAT ET to install this sensor?
A: While the sensor is plug-and-play, we recommend using CAT ET to clear any stored diagnostic codes and verify the temperature reading after installation.
Q6: What is the correct torque for this sensor?
A: 15–25 Nm (11–18 ft-lbs) . Do not overtighten – the brass housing can crack.
Q7: Can I use this sensor for both coolant and intake air?
A: Yes, if the resistance curve is the same. However, some sensors have different connectors or calibration. Always match the original part number.
Q8: Is this sensor in stock for immediate shipping?
A: Yes – COGENG maintains stock of 500+ units. Orders ship within 24–48 hours.
Q9: How long does shipping take?
A:
Express (DHL/FedEx/UPS/TNT): 3–7 business days worldwide.
Air freight: 7–12 days.
Sea freight: 20–40 days.
Q10: How do I place a trial order?
A: Contact your COGENG distributor. MOQ is 1 piece.
| Code | Description | Likely Issue |
|---|---|---|
| 110-03 | Engine Coolant Temp Sensor – Voltage High | Sensor open circuit / wiring |
| 110-04 | Engine Coolant Temp Sensor – Voltage Low | Sensor shorted / wiring |
| 172-03 | Intake Air Temp Sensor – Voltage High | Sensor open circuit / wiring |
| 172-04 | Intake Air Temp Sensor – Voltage Low | Sensor shorted / wiring |
| 178-03 | Fuel Temperature Sensor – Voltage High | Sensor open circuit / wiring |
| 178-04 | Fuel Temperature Sensor – Voltage Low | Sensor shorted / wiring |
If codes persist after sensor replacement, check the wiring harness for damage.
| Parameter | 128-8945 | 342-2924 |
|---|---|---|
| Sensor Type | NTC Thermistor | NTC Thermistor |
| Temperature Range | -40°C to +150°C | -40°C to +150°C |
| Resistance @ 25°C | ~10,000 Ω | ~10,000 Ω |
| Resistance @ 100°C | ~1,000 Ω | ~1,000 Ω |
| Connector Type | 2-pin Deutsch | 2-pin Deutsch |
| Thread Size | 1/8-27 NPT | 1/8-27 NPT or M10x1 |
| Hex Size | 17mm / 19mm / 22mm | 17mm / 19mm / 22mm |
| Housing Material | Brass / Stainless Steel | Brass / Stainless Steel |
| Seal Material | Nitrile rubber (NBR) | Nitrile rubber (NBR) |
| Operating Voltage | 5V DC | 5V DC |
| ISO Standard | ISO9001:2015 | ISO9001:2015 |
| Country of Origin | China (Guangdong) | China (Guangdong) |
| HS Code | 90259000 | 90259000 |
To ensure we ship the correct sensor (128-8945 vs 342-2924), please provide:
Machine Model: CAT 325C.
Engine: CAT C9 (confirm).
Old Part Number: (Check the stamp on the old sensor).
Sensor Location: Coolant / Intake Air / Fuel.
Photo of Old Sensor: (Highly recommended – helps identify connector and thread type).
✅ In Stock – Ready to Ship.
✅ MOQ 1 piece accepted for trial orders.
📞 Contact COGENG supplier today to place your order!
*Shipping Details Delivery Return*
Sales Price:
The displayed price is for reference only. Please contact COGENG sales support for the exact price.
Shipping Method:
Sea, land, or air transport; the specific method is determined based on the nature of the shipment.
Estimated Delivery Time:
Based on the dispatch time from the logistics carrier; the displayed arrival time serves as the reference.
Contact information is provided at the bottom of the page.
Merchant Return Policy:
Products shipped are not eligible for return or exchange.
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