Error P1778 on Nissan: what it means, how to diagnose and fix it

Fault code P1778 - one of the most common problems in automatic transmissions Nissan with control solenoids. This error indicates incorrect operation Torque converter lockup (TCC) solenoid valve or related circuits. Owners Qashqai, X-Trail, Teana and other models often encounter it after 100–150 thousand kilometers, but the reasons may lie in both mechanics and electronics.

In this article we will look at unique diagnostic algorithm P1778 for Nissan, which allows you to identify the exact cause without unnecessary costs for replacing parts. You will learn how to check solenoids with a multimeter, what symptoms cannot be ignored, and why the standard error reset is via ECU Reset gives only a temporary effect. The material is based on data from service manuals Nissan and the experience of craftsmen specializing in automatic transmissions RE0F10A/RE0F11A.

What is error P1778 and why does it appear?

Code P1778 stands for "Torque Converter Clutch Solenoid Performance" — malfunction of the torque converter lock-up solenoid. This valve is responsible for smoothly engaging/disengaging the torque converter lockup (TCC), which affects:

• 🔄 Torque transmission from engine to transmission without slipping.
• ⚡ Fuel economy by reducing losses in the torque converter.
• 🛣️ Driving comfort on the highway (no “jerks” during acceleration).

When the automatic transmission control unit (TCM) detects a discrepancy between the commanded and actual solenoid position, it records P1778 and can transfer the box to emergency mode (limited gears, hard shifts). The reasons are divided into 3 groups:

Fault type	Examples	Frequency of occurrence
Electrical	Broken wiring, oxidation of contacts, malfunction TCM	30%
Mechanical	Solenoid wear, valve body channels clogged, seals damaged	50%
Hydraulic	Low oil pressure, incorrect ATF viscosity, clogged filter	20%

Feature P1778 on Nissan — its “floating” character. The error can only appear when it is cold, during sudden acceleration, or after a long drive in a traffic jam. This complicates diagnosis, since standard scanning OBD-II does not always show up-to-date data.

P1778 Symptoms: When to Sound the Alarm

Not all signs of a bad TCC solenoid are obvious. For example, jerking when changing gears at speeds of 60–80 km/h they are often attributed to automatic transmission fatigue. However, there are specific symptoms that directly indicate P1778:

• 🚗 Jerks during acceleration (especially in 3rd-4th gear), as if the car was being “kicked” from behind.
• 🔥 Increased engine speed on the highway (tachometer shows 3000–3500 rpm at 100 km/h).
• 🛑 Sunbathing Check Engine after driving uphill or with a trailer.
• 🔄 Torque converter lockup delay (it feels like a “drawdown” when accelerating).

Critical symptom - loss of power when overtaking, when the automatic transmission “thinks” for 2–3 seconds before switching. This indicates that the TCC solenoid is not coping with the load and TCM forcibly disables the lock. In such cases, further operation without repair is fraught with:

⚠️ Attention: Long-term driving with a faulty TCC solenoid leads to overheating of the automatic transmission oil and accelerated wear of the clutches. If you ignore P1778 more than 500 km, the risk of overhauling the gearbox increases by 40%.

On Nissan Almera N16 And Primera P12 with automatic transmission RE4F04B the error is often accompanied by hum from the box in neutral gear. This is due to the fact that a faulty solenoid provokes increased pressure in the valve body even at idle.

Step-by-step diagnostics: how to find the cause of P1778

The troubleshooting algorithm depends on the availability of diagnostic equipment. If you have a scanner that supports Nissan Consult (For example, Launch X431 or Autel MaxiCOM), start by reading real data (Live Data) by parameters:

• 📊 TCC Solenoid Duty Cycle (should be 0% when unlocked and 80-100% when locked).
• 📊 Turbine Speed Sensor (turbine wheel rotation speed).
• 📊 Transmission Fluid Temperature (automatic transmission oil temperature).

If you don't have a scanner, use multimeter and visual inspection. Here is a checklist for checking it yourself:

Check the level and condition of the ATF oil (should be red, without a burnt smell)

Inspect the wiring from the TCM to the solenoids (look for melted or oxidized contacts)

Measure TCC solenoid resistance (normal: 10-15 ohms at 20°C)

Check the voltage at the solenoid connector (should be 12V with ignition on)

Carry out a test drive and record the conditions under which the error occurs -->

To check the solenoid with a multimeter:

1. Remove the automatic transmission pan and find the valve body (on Nissan it is usually gray with yellow connectors).
2. Disconnect the TCC solenoid connector (it is marked as SL3 or TCC).
3. Connect the multimeter probes to the solenoid contacts and measure the resistance.

⚠️ Attention: On models Nissan Murano Z51 And Pathfinder R51 The TCC solenoid is integrated into the solenoid block (soleniod pack). Replacing it requires complete disassembly of the valve body - do not try to do this without experience!

How can you tell the difference between a bad solenoid and a TCM problem?

If, when measuring resistance, the solenoid shows normal (10-15 ohms), but error P1778 remains, the problem may be in the TCM control unit. In this case, check:

1. The presence of corrosion on the TCM board (especially in the area of the solenoid driver chips).

2. Condition of solder connections - resistors R12 and R15 often fall off (on TCM boards for RE0F10A).

3. TCM power (should be 5V at pin 16 of the connector).

If the TCM is faulty, it can be reflashed or replaced with a used one, followed by adaptation through Nissan Consult III+.

Top 5 causes of error P1778 on Nissan and how to fix them

Based on service center statistics, here are the most common reasons P1778 and ways to eliminate them:

Reason	Models where it occurs most often	Solution	Repair cost (RUB)
TCC solenoid wear	Qashqai J10, X-Trail T31	Replacing a solenoid or the entire solenoid assembly	8 000 – 15 000
Valve block clogged	Teana J32, Maxima A35	Flushing the valve body + replacing ATF	12 000 – 20 000
TCM malfunction	Murano Z50, Pathfinder R50	Board repair or block replacement	15 000 – 30 000
Broken wiring	Almera N16, Primera P12	Restoring contacts, replacing harness	3 000 – 7 000
Incorrect ATF oil	All models with automatic transmission RE0F10A/RE0F11A	Complete oil change Nissan Matic-S	5 000 – 10 000

Pay special attention ATF oil. On Nissan with new type TCC solenoids (after 2010) use of universal type oils Dexron III causes the valve to jam. Official requirement - Nissan Matic-S (catalog number KLE52-00004).

Replacing the TCC Solenoid: Step-by-Step Instructions

If diagnostics confirm a solenoid malfunction, you can replace it yourself (on models before 2015). You will need:

• 🔧 Set of heads and socket wrenches (10 mm, 12 mm).
• 🔧 Flat screwdriver for removing clips.
• 🔧 New TCC solenoid (original - 31397-31X00 or 31397-31X01).
• 🔧 Sealant for pallet (Loctite 574).

Work order:

1. Drain the oil from the automatic transmission (unscrew the drain plug or remove the pan).
2. Remove the tray, clean it and the magnets from metal shavings.
3. Disconnect the valve body connector and unscrew the fastening bolts (usually 10 pieces per 10 mm head).
4. Carefully remove the valve body and turn it over. The TCC solenoid is located in the center (marked with a yellow mark).
5. Replace the solenoid, reassemble everything in reverse order. Use the new filter (31726-31X00) and sealant.
6. Refill with fresh oil Nissan Matic-S (volume - 8–9 liters for a complete replacement).

⚠️ Attention: On Nissan Juke F15 And Note E12 with automatic transmission JF015E The TCC solenoid is built into the valve plate housing. Replacing it requires complete disassembly of the box - trust this to specialists!

After replacing the solenoid you must:

1. Reset automatic transmission adaptations via scanner (command TCM Reset).
2. Carry out throttle valve training (Throttle Valve Closed Position Learning).
3. Drive 20–30 km in gentle mode (without sudden acceleration) to TCM recorded new parameters of the solenoid.

Common repair mistakes and how to avoid them

Many owners Nissan facing relapse P1778 after a seemingly successful renovation. Here are common mistakes and how to prevent them:

• 🔧 Use of non-original solenoids. Cheap analogues (for example, from Meyle or Febi) often have inaccurate resistance characteristics, which leads to incorrect TCC operation. Buy only original or proven brands (Ajusa, Zekkert).
• 🛢️ Incomplete oil change. If, when replacing a solenoid, you do not flush the valve body and replace the filter, dirt particles will quickly damage the new solenoid. Use flushing fluid Wynn's TransClean.
• 🔌 Ignoring TCM Check. On Nissan With a mileage of more than 150 thousand km, the solenoid drivers in the control unit often fail. If you don't check TCM using an ohmmeter (the resistance between legs 1–8 should be 60–80 ohms), the new solenoid will burn out.

Another common problem is incorrect automatic transmission training after repair. On Nissan with systems CVT (For example, Juke or Qashqai J11) after replacing the solenoids, the following is required:

1. Reset wear counters via Nissan Consult (command CVT Fluid Deterioration Data Reset).
2. Execute procedure CVT Learning (learning of switching points).

Without these steps, the box will work in emergency mode, and the error P1778 will return in 50–100 km.

Prevention: How to prevent P1778 from coming back

To avoid the error reoccurring, follow these recommendations:

• 🔄 Change ATF oil every 60,000 km (even if the manufacturer indicates 90,000 km). Use only Nissan Matic-S or Idemitsu ATF Type-M.
• 🚗 Avoid towing and trailering when the oil temperature is above 100°C (the icon lights up on the instrument panel AT OIL TEMP).
• ⚡ Check the wiring once a year: oxidation of contacts on the connector TCM - a common cause of false errors.
• 📊 Read errors every 10,000 km even if there are no symptoms. Early diagnosis allows you to eliminate P1778 replacing one solenoid, and not the entire valve body.

On models Nissan with automatic transmission RE0F10A (For example, Teana J32 or Maxima A35) it is useful to wash the valve body with a special liquid once every 2 years (Liqui Moly ATF Reiniger). This removes varnish deposits that will block the solenoid passages over time.

FAQ: Answers to frequently asked questions about error P1778

Is it possible to drive with a P1778 code if there are no obvious symptoms?

For a short time (up to 200–300 km) - yes, but it’s not worth the risk. Even if there is no jerking, a faulty TCC solenoid will result in:

• Increased wear of torque converter clutches.
• Oil overheating (every +10°C above normal reduces the life of the automatic transmission by 15%).
• Increased fuel consumption by 5–10%.

If the error appears only when cold, check wiring And TCM contacts -Often the problem is oxidation.

The TCC solenoid was replaced, but the error remained. What to do?

Probable reasons:

1. Torque converter faulty (friction lining or bearing wear). Check the torque converter shaft play - if it is more than 1.5 mm, replacement is required.
2. The valve body channels are clogged. On Nissan with a mileage of >150 thousand km, the oil supply channels to the solenoids are often clogged. The solution is ultrasonic washing of the valve body.
3. TCM firmware failure. On models after 2012 (for example, Qashqai J11) requires flashing the control unit via Nissan Consult III+.

Start by checking oil pressure in automatic transmission (norm: 3.5–4.5 bar at 2000 rpm). If the pressure is low, the problem is in the oil pump or filter.

How much does it cost to repair a P1778 in service?

The cost depends on the reason and model:

Type of repair	Cost (RUB)	Timing (hours)
TCC Solenoid Replacement	8 000 – 15 000	3–5
Valve body flushing + oil change	12 000 – 20 000	4–6
TCM repair/replacement	15 000 – 30 000	2–3 (no waiting for details)
Overhaul of automatic transmission (torque converter + valve body)	50 000 – 90 000	10–15

On Nissan with warranty (up to 5 years) repairs according to P1778 may be free if the error is caused by a defective solenoid or TCM. Check if the recall campaign is active for your model (for example, for X-Trail T32 2014–2016 there was a service bulletin NTB15-079 for problems with solenoids).

Can P1778 be reset without repair?

Technically yes, but this is a temporary solution. Methods:

• Disconnect the battery terminal for 10 minutes (it will reset the errors, but they will return after 50–100 km).
• Use scanner to reset DTC (For example, Launch CReader).
• On some models, rebooting helps TCM through the sequence: turn off the ignition → press the gas pedal all the way → turn on the ignition → wait 10 seconds → release the pedal.

However, if the reason P1778 mechanical (wear of the solenoid or torque converter), resetting only masks the problem and aggravates the wear of the automatic transmission.

What kind of oil should I put in a Nissan automatic transmission to avoid P1778?

For most models (Qashqai, X-Trail, Teana) with automatic transmission RE0F10A/RE0F11A officially recommended:

• Nissan Matic-S (original, article KLE52-00004) is the optimal choice.
• Idemitsu ATF Type-M - complete analogue, approved Nissan.
• Mobil ATF 3309 — allowed for automatic transmissions until 2010.

It is prohibited to use:

• Dexron II/III — leads to jamming of the solenoids.
• Universal ATF (For example, Castrol Transmax) - not compatible with clutches Nissan.
• Oils with markings JWS 3309unless they are certified for Matic-S.

Volume for a complete replacement: 8–9 liters (for CVT - 7.5 l). After changing the oil, be sure to reset the aging counter through the scanner (ATF Deterioration Data Reset).