Nissan Sunny FB15 - a reliable car, but even with time, key elements of the cooling system fail. One of the most vulnerable nodes is coolant temperature sensor (DTOZH). Its malfunction leads to engine overheating, increased fuel consumption and even failure to start the engine. In this article we will look at how to independently diagnose and replace the DTOZH with Sunny FB15without resorting to expensive services.

The coolant temperature sensor is a thermistor that changes resistance depending on temperature. The electronic control unit (ECU) reads this data and adjusts engine operation: from the composition of the fuel mixture to the ignition timing. On Nissan Sunny FB15 with engines GA15DE And GA16DE The DTOZH is located in the thermostat housing, which simplifies access, but requires care when replacing.

If you notice that the temperature arrow on the dashboard behaves inappropriately, the engine takes a long time to warm up, or, conversely, overheats for no apparent reason, this sensor may be to blame. Next, we’ll tell you how to check it, what errors it gives, and give step-by-step instructions for replacement with photos and videos.

Signs of a malfunction of the coolant temperature sensor on Nissan Sunny FB15

The first signal about problems with DTOZH - Incorrect temperature readings on the dashboard. The needle may freeze at zero, jump, or show overheating when the engine is cold. But there are other symptoms that are often ignored:

  • 🔥 The engine takes a long time to warm up - especially noticeable in winter, when the stove blows cold air longer than usual.
  • ⛽ Increased fuel consumption — The ECU “thinks” that the engine is cold and enriches the mixture.
  • 🚗 Poor hot start — the engine stalls or is difficult to start after a short stop.
  • ⚠️ Check Engine - an error appears P0115 (DTOZh circuit malfunction) or P0116 (signal outside the permissible range).
  • 💨 Cooling fan runs constantly or does not turn on at all.

On Sunny FB15 With a manual transmission, a faulty DTO can also cause jerks during acceleration - the ECU incorrectly adjusts the fuel supply. If you observe at least 2-3 signs from the list, the sensor needs to be checked.

⚠️ Attention: Do not confuse DTOZH with temperature indicator sensor (it goes to the dashboard). On FB15 they are separate, and failure of the second one does not affect the operation of the engine, but can be misleading during diagnostics.
📊 How often do you check the cooling system?
  • Once a year
  • Only when problems arise
  • Never checked
  • I monitor the condition myself

Where is the coolant temperature sensor located? Nissan Sunny FB15?

On Sunny FB15 (1990–1999) with engines GA15DE And GA16DE DTOZH installed in thermostat housing, which is attached to the cylinder head on the intake manifold side. To see it:

  1. Open the hood and remove the decorative engine cover (if equipped).
  2. Locate the upper radiator hose - it leads to the thermostat.
  3. DTOZH is located next to the pipe, it fits two-pin connector (black or grey).

The photo below shows the exact location (clickable):

Access to the sensor is free, but before replacing it is necessary release pressure in the cooling system, otherwise hot liquid will gush out when unscrewing. To do this:

  1. Allow the engine to cool (at least 1 hour).
  2. Open the expansion tank cap.
  3. Cover the neck with a rag and press it slowly to release the air.
⚠️ Attention: If you have recently added antifreeze, check the level before starting work. On FB15 cooling system volume - 6.5 liters, and when replacing the sensor you can lose up to 0.5 liters.

How to check the coolant temperature sensor Nissan Sunny FB15?

Before replacing the DTOZH, you need to check it - perhaps the problem is in the wiring or connector. You will need multimeter (in ohmmeter mode) and a thermometer (you can use infrared).

Step 1: Resistance Test

Disconnect the connector from the sensor and measure the resistance between its contacts at different temperatures. Compare the readings with the table:

Temperature (°C) Resistance (kOhm)
0 (ice water) 7,0–9,0
20 (room) 2,3–3,0
80 (working temperature) 0,3–0,5
100 (boiling water) 0,1–0,2

If the resistance does not meet the standards or is equal to 0/∞ (break), the sensor is faulty.

Step 2: Check Voltage

Reconnect the connector and check the voltage at the contacts with the ignition on (do not start the engine!). On one contact there should be 5 V (powered by the ECU), on the second - 0 V (mass). If there is no voltage, the problem is in the wiring.

Disconnect the sensor connector|Check the resistance with a multimeter|Compare the readings with the table|Check the voltage on the contacts (5 V and 0 V)|Inspect the connector for oxidation-->

Step 3: Visual Inspection

Inspect the sensor for:

  • 🔍 Corrosion on the connector contacts.
  • 💧 Antifreeze leaks around the body.
  • 🔧 Cracks or deformations.

If the sensor is “wet” or covered with a white coating (antifreeze deposits), it needs to be replaced.

What to do if the sensor is working, but the error remains?

If the DTOZH is normal, but there is an error P0115/P0116 does not disappear, check:

1. Integrity of the wiring from the sensor to the ECU (often frays near the intake manifold).

2. Oxidation of contacts in the ECU connector (on FB15 the unit is located under the glove compartment).

3. The ECU itself sometimes “glitches” due to moisture or poor grounding.

What errors does a faulty DTOZh produce? Nissan Sunny FB15?

On Sunny FB15 with diagnostic system OBD-I (before 1996) or OBD-II (after 1996) a faulty coolant temperature sensor causes the following errors:

Error code Description Possible reason
P0115 Coolant temperature sensor circuit malfunction Wire break, contact oxidation, sensor failure
P0116 Coolant temperature sensor range/performance The sensor produces incorrect values (for example, -40°C when the engine is warm)
P0117 Low signal level of the coolant temperature sensor Short circuit to ground or ECU fault
P0118 High signal level of the coolant temperature sensor Open circuit or short circuit to +12 V

On models before 1996, errors are read self-diagnosis method:

  1. Insert the key into the ignition.
  2. Within 5 seconds, press and hold the gas pedal all the way.
  3. Turn the key to position ON (without starting the engine).
  4. Read codes by flashing light Check Engine (For example, 12 flashes - pause - 1 flash = error 121).

For FB15 with OBD-II (after 1996) use a scanner or adapter ELM327. Errors are erased after the cause is eliminated, but if they appear again, the problem is not solved.

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On Nissan Sunny FB15 1995–1996 sometimes resetting the ECU helps: disconnect the negative terminal of the battery for 10 minutes, then connect it back. This will reset adaptive settings and temporarily eliminate false errors.

Which coolant temperature sensor is suitable for Nissan Sunny FB15?

On Sunny FB15 Sensors with article numbers are installed:

  • 🔧 Original: 22630-4M000 or 22630-4M005 (depending on the year of manufacture).
  • 🔧 Analogues:
    • NGK 13281 (Japan)
    • Denso 550301-5600 (Japan)
    • Bosch 0 280 130 019 (Germany),
    • Vemo V10-72-0008 (Germany).

Cost of the original sensor - 1,500–2,500 rub., analogues - 500–1,200 rub.. When purchasing, pay attention to:

  • 📏 Thread size - should be M12x1.25.
  • 🔌 Connector type - on FB15 A two-pin connector with a plastic retainer is used.
  • 🌡️ Temperature range - must cover from -40°C to +130°C.

Do not buy sensors without markings or with the inscription “universal” - they may not match the resistance. Also avoid Chinese branded knockoffs NGK or Denso (can be distinguished by poor quality packaging and the absence of a hologram).

⚠️ Attention: On Sunny FB15 with air conditioning, the coolant temperature sensor affects the operation of the compressor. If after replacement the air conditioner stops turning on, check the sensor circuit - the ECU may block the climate control if the readings are incorrect.

Step-by-step instructions for replacing the DTOZH with Nissan Sunny FB15

Replacing the coolant temperature sensor with FB15 takes 20–30 minutes and does not require special tools. You will need:

  • 🔧 Key on 19 mm (or ratchet head).
  • 🧤 Gloves (antifreeze is toxic!).
  • 🧻 Rags and container for draining coolant (volume ~0.5 l).
  • 🔌 New sensor and copper sealing washer (included or purchased separately).
  • 🔥 Hairdryer or WD-40 (if the sensor is “stuck”).

Sequence of actions:

  1. Preparation:
    • Place the car on a level surface.
    • Allow the engine to cool (at least 1 hour).
    • Disconnect the negative terminal of the battery.
  2. Antifreeze drain (partial):
    • Place a container under the thermostat.
    • Unscrew the sensor 1–2 turns to release the pressure and drain ~200 ml of liquid.
    • If the antifreeze is clean, you can add it back.
  3. Sensor replacement:
    • Disconnect the connector from the DTOZH.
    • Key on 19 mm unscrew the sensor counterclockwise.
    • Install a new sensor with new sealing washer and tighten it momentarily 15–20 Nm (do not overtighten!).
    • Connect the connector.
  4. Check:
    • Add antifreeze to the level (if necessary).
    • Start the engine and check for leaks.
    • Treat errors with a scanner or self-diagnosis method.

If after replacement there is an error P0115 left, check:

  • 🔌 Contact density in the connector.
  • 🔧 Wiring integrity (often rubs against the intake manifold).
  • 📊 ECU settings (sometimes adaptations need to be reset).
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When installing a new sensor be sure to use a new sealing washer - the old one can leak antifreeze, which will lead to false readings and overheating.

Frequent mistakes when replacing DTOZH with Nissan Sunny FB15

Even experienced car owners make mistakes that lead to repeated breakdowns. That's what can't do when replacing the sensor:

  • 🚫 Use old sealing washer - it deforms when tightened and does not seal the connection.
  • 🚫 Drag the sensor - this leads to damage to the threads in the thermostat housing (aluminum is soft!).
  • 🚫 Fill in antifreeze immediately after replacement — you first need to bleed the air from the system, otherwise an air lock will form.
  • 🚫 Ignore errors after replacement - if Check Engine does not go out, the problem is not in the sensor.
  • 🚫 Buy a sensor without checking the resistance - even a new one can be defective.

Another common mistake is confuse DTOZH with a fan sensor. On FB15 The cooling fan is turned on by a signal from separate sensor, which is located in the radiator (not in the thermostat!). If the fan does not work, check both sensors.

Also do not forget that after replacing the DTOZh may be required reset ECU adaptations, especially if the error has been hanging for a long time. On Sunny FB15 this is done:

  • Disconnecting the battery for 10–15 minutes.
  • Or using a scanner (command Reset ECU).

FAQ: Frequently asked questions about DTOZH on Nissan Sunny FB15

Is it possible to drive with a faulty DVT?

Short-term - yes, but it is fraught with:

  • 🔥 Engine overheating (the ECU does not correct the ignition angle).
  • ⛽ Increased fuel consumption (up to +20%).
  • 🚗 Poor launch, especially in cold weather.

If the sensor “lies” in the direction of lowering the temperature, the risk of overheating is minimal, but the engine will operate in a suboptimal mode.

What antifreeze should I fill in after replacing the DTOZH?

On Sunny FB15 filled from the factory green antifreeze based on ethylene glycol (specification Nissan Coolant L248). Modern analogues:

  • CoolStream A-110 (green, G11),
  • Sintec Unlimited (purple, G12++),
  • Motul Inugel Optimal (orange, G13).

System volume - 6.5 liters. You cannot mix antifreeze of different colors!

Why does the engine run unstably after replacing the DTOZH?

Probable reasons:

  • 🔌 Loose contact in the sensor connector.
  • 🌡️ Air lock in the cooling system (you need to bleed the air through the fitting on the stove pipe).
  • 📊 The ECU did not reset the adaptation (you need to disconnect the battery for 10 minutes).
  • 🔧 Defective sensor (check the resistance!).
Is it possible to clean the old DTOZH?

No. The temperature sensor is a thermistor with a coating that degrades over time. Cleaning or washing will not restore its performance. The only option is replacement.

Where to buy DTOZH for Sunny FB15 inexpensive?

Optimal options for price/quality:

  • 🛒 Exist.ru — original ~1,800 rub., analogues from 600 rub.
  • 🛒 Autodoc - there are often discounts on NGK And Denso.
  • 🛒 Local disassembly - a used sensor will cost 300–500 rubles, but there is no guarantee.

When purchasing, specify that you need a sensor for GA15DE/GA16DE - for diesel Sunny (For example, CD17) other DTOZH are installed!