Description
Product Video
1. Why Genuine Matters on a $30 Sensor – The Real Cost of a Fake
A differential pressure sensor measures clogging of the hydraulic return filter or engine air filter. It looks simple. But a non‑genuine sensor can cost you far more than its purchase price.
| Failure Mode | Cheap Copy | Hitachi Genuine (4339559) |
|---|---|---|
| False alarm | Triggers warning light when filter is clean | Accurate reading – no unnecessary downtime |
| No alarm | Fails to warn – filter bypasses, debris circulates | Reliable warning – you change filter on time |
| Signal drift after 500 hours | Common (thermal drift) | Tested to 5,000+ hours |
| Connector fit | Loose pins – intermittent signal | Tight fit – gold‑plated contacts |
| Consequence of failure | Unplanned shutdown or major hydraulic damage | Predictable maintenance |
The math: A clogged bypassed hydraulic filter can send debris through the main pump. Pump replacement: $5,000–$8,000. Genuine sensor: ~$30. False economy is expensive.
2. Three Ways to Spot a Fake 4339559 – Visual Inspection Guide
We have seen counterfeit Hitachi sensors in the market. Here is how to tell real from fake before you install.
| Inspection Point | Genuine Hitachi 4339559 | Common Fake |
|---|---|---|
| Molding seam | Clean, even, no flash | Rough, uneven, or excess plastic |
| Part number engraving | Laser etched, sharp, permanent | Printed or shallow stamp – rubs off |
| Connector pin color | Gold‑plated (yellowish) | Tin‑plated (silver) – corrodes faster |
| O‑ring material | Fluorocarbon (brownish), fuel resistant | Nitrile (black) – swells in oil |
| Weight | 28g ±1g | Usually lighter (<25g) or heavier (metal added) |
| Box label | Hitachi construction logo, batch code | Generic label or missing |
When in doubt, send us a photo of the sensor and box – we will authenticate within 2 hours.
3. What This Sensor Actually Does – And What Happens When It Lies
On EX200-3E, EX200-2, EX200-3, the differential pressure sensor (4339559) monitors the hydraulic return filter. The ECU compares pressure before and after the filter.
| Sensor Reading | Actual Condition | ECU Action |
|---|---|---|
| Normal | Filter clean | Nothing |
| High differential | Filter clogging | Warning light + optional auto‑throttle reduction (if equipped) |
| No signal | Sensor failed | Check engine light + limp mode (reduced pump flow) |
If a fake sensor reads “normal” when the filter is clogged: The filter bypass valve opens. Unfiltered oil circulates. Pump and valve wear accelerates. You may not notice until a pump fails – months later.
4. Real Case – A Workshop That Learned the Hard Way
A repair shop in Manila bought six cheap “compatible” sensors for EX200‑3 rebuilds. Within three months, two machines came back with filter bypass warnings – but the sensors showed normal. The actual filter was clogged; the sensors were dead.
They replaced one with our genuine 4339559 and tested: the warning lit exactly when the filter reached spec. The other five cheap sensors? All failed to read correctly. They threw them out and ordered genuine.
The shop owner’s quote: “The cheap sensor saved me $20 each. It cost me two return trips ($400 each) and angry customers. Never again.”
5. Installation Checklist – Avoid Common Mistakes
| Step | What to Do | Why |
|---|---|---|
| 1 | Clean the mounting port | Dirt entering the sensor tip blocks the pressure port |
| 2 | Replace the copper sealing washer (if equipped) | Old washer leaks – sensor reads low |
| 3 | Torque to 18–22 Nm (not more) | Overtightening cracks the plastic housing |
| 4 | Apply dielectric grease to connector pins | Prevents moisture ingress and pin corrosion |
| 5 | After installation, test with a known restriction | Use a ball valve to simulate clog – verify warning light comes on |
We include a one‑page illustrated guide with every sensor.
6. Product Contents – Simple and Complete
| Item | Quantity | Note |
|---|---|---|
| Differential pressure sensor 4339559 | 1 | Hitachi genuine, made in Japan |
| Copper sealing washer | 1 | Pre‑installed or separate (depends on batch) |
| Protective cap | 1 | Removable before install |
| Paper box | 1 | Hitachi‑style packaging (batch code printed) |
Not included: Wiring harness, filter housing, or diagnostic tool.
7. Ordering & Delivery
| Item | Detail |
|---|---|
| Compatibility | Hitachi EX200-2, EX200-3, EX200-3E (also EX220, EX270 with same filter housing – verify) |
| MOQ | 1 piece |
| Lead time | 6–8 working days |
| Packaging | Paper box inside reinforced carton |
| Payment | T/T, XTransfer, PayPal, Western Union |
| Supply capacity | 300 pcs/month (limited genuine stock) |
| Warranty | 6 months (manufacturing defects only – no warranty against clogged filters or debris damage) |
8. Before You Order – Verification
Because counterfeit sensors are common, we require one of the following to confirm you receive genuine:
Option A: Order directly from us – we supply from authorized Japanese source.
Option B: Send a photo of your old sensor (top and side) – we compare visually and confirm.
We do not sell “compatible” or “aftermarket” versions of this sensor. Only genuine Hitachi 4339559.
Don’t risk your hydraulic system to save a few dollars. Install genuine – and know your warnings are real.
