Error B1401 on Nissan Almera Classic: decoding, diagnostics and repair

Error B1401 on Nissan Almera Classic (body N16) is one of the most common anti-lock brake system (ABS) problems encountered by owners of this car. The code indicates a fault in the circuit Right front wheel speed sensor, but often the problem lies deeper - from oxidized contacts to breakdown of the ABS unit itself. In this article, we will look at why the error occurs, how to correctly diagnose it, and what steps to take to eliminate it - from simple cleaning of connectors to replacing components.

It is important to understand that ignoring B1401 may cause ABS failure in critical situation, although the braking system will remain operational (but without anti-lock). The problem is especially relevant for Almera Classic 2006-2012 model years, where ABS sensors and wiring often suffer from corrosion. We have collected proven solutions, including nuances for cars with engines QG15DE And QG16DE, as well as advice on choosing spare parts.

What does error B1401 mean on Nissan Almera Classic?

Code B1401 in the self-diagnosis system Nissan stands for "Right Front Wheel Speed Sensor Circuit Malfunction" — malfunction of the rotation speed sensor circuit right front wheel. Unlike engine errors (eg. P0300), this code relates exclusively to the ABS system and does not affect the operation of the power unit. However, its appearance may be accompanied by:

• 🔴 ABS light on on the dashboard (sometimes flashes when driving).
• 🔧 Disabling the anti-lock braking system — the brakes work, but the wheels may lock if pressed hard.
• ⚠️ By activating the "BRAKE" icon (if the problem affects the hydraulic unit).
• 📉 Incorrect speedometer readings (rare, but possible if the signal is interrupted).

On Almera Classic The right front wheel sensor is located on wheel bearing and is connected to the ABS unit via a wiring harness. Error B1401 can occur both due to mechanical damage (for example, a broken wire) and due to electronic failures - for example, corrosion of contacts in the control unit connector. In 30% of cases, the problem is solved by simply cleaning the contacts, but sometimes it is necessary to replace the sensor or even the entire ABS unit.

⚠️ Attention: If together with B1401 the lamp lights up ESP (if your equipment has one), this may indicate a malfunction of the ABS hydraulic pump. In this case, it is better to entrust the diagnosis to specialists - independent repairs are fraught with leakage of brake fluid.

Reasons for error B1401

On Nissan Almera Classic code B1401 provoke both “minor” problems (dirt, corrosion) and serious breakdowns. Here are the main reasons, ranked by frequency of occurrence:

1. Oxidation or broken wiring is the most common culprit. The wires from the sensor to the ABS unit run near the wheel arch and often fray or rust.
2. ABS sensor malfunction — internal winding break or damage to the magnetic core (especially after impacts on the hub).
3. Damage to the gear rotor (combs) on the hub - chipped or worn teeth lead to an unstable signal.
4. Corrosion in the ABS unit connector — contacts oxidize due to moisture ingress (typical for cars with mileage >150 thousand km).
5. ABS control unit malfunction - rare, but occurs during power surges or after unqualified repairs.

Feature Almera Classic — poor protection of the wiring of the ABS sensors. For example, on models before 2010, the harness often rubs against the suspension bracket, and after 2010, the problem shifts to the connectors (due to low quality seals). Also error B1401 may appear after replacing the wheel bearing if the sensor was damaged during dismantling.

How to diagnose error B1401 yourself

For accurate diagnosis B1401 on Nissan Almera Classic you will need:

• 🔧 Multimeter (to check the resistance of the sensor and circuit).
• 🔍 Diagnostic scanner (For example, ELM327 or Launch CReader).
• 🛠️ Screwdriver and jack (to access the sensor).
• 🧴 WD-40 or contact cleaner (for cleaning connectors).

Step 1: Read errors with scanner. Besides B1401, there may be associated codes, for example:

• C1130 — malfunction of the left front wheel sensor circuit (if the problem is symmetrical).
• U1000 — loss of communication with the ABS unit (indicates problems with power supply or “brains”).

Step 2: Check the ABS sensor with a multimeter. The normal resistance of a working sensor is Almera Classic — 800–1400 Ohm. If the device shows 0 ohm (short circuit) or ∞ (break), the sensor must be replaced. Also check the circuit for a short to ground.

Step 3: Inspect the wiring and connectors. Please note:

• 🔌 Sensor chip condition - oxidation or moisture leakage.
• 🔗 Wire integrity from the sensor to the ABS block (especially in places of kinks).
• 🧲 Toothed rotor on hub — no chips and a uniform gap (~1 mm) between the sensor and the comb.

Read errors with a scanner|Check the sensor resistance (800–1400 Ohm)|Inspect the wiring for breaks|Clean the contacts in the ABS unit connector|Check the gap between the sensor and the rotor-->

Step-by-step instructions for resolving error B1401

If diagnostics reveal a problem with the sensor or wiring, follow this algorithm (for Nissan Almera Classic with engines QG15DE/QG16DE):

1. Cleaning contacts and connectors

Start with the simplest thing - cleaning the contacts in the sensor connector and the ABS unit:

1. Disconnect the sensor chip (located next to the hub).
2. Process contacts electrical wiring cleaner (For example, Kontakt 60).
3. Check the ABS unit connector (located under the hood, next to the vacuum booster). Dirt often accumulates there.

2. Replacing the ABS sensor

If the sensor is faulty, replace it with a new one. For Almera Classic fit original parts:

• 🔧 Original: 40520-4M000 (Nissan) or 259603800R (Renault, similar).
• 💰 Analogues: Febi (article 25960), TRW (JGS1033).

The cost of the original is ~2,500 ₽, the analogue is from 1,200 ₽. When replacing:

• Disconnect the battery (reset errors after repair).
• Remove the wheel and disconnect the sensor chip.
• Unscrew the sensor mounting bolt (key on 10 mm).
• Install the new sensor, maintaining a gap of ~1 mm to the rotor.

3. Wiring repair

If the problem is in the wires, proceed as follows:

• 🔍 Find the break point (most often near the sensor chip or in the harness under the hood).
• 🛠️ Strip and solder the wires, insulating them with heat shrink.
• 🔌 Secure the tourniquet with plastic clamps to avoid repeated rubbing.

After renovation be sure to clear errors through a scanner or by disconnecting the battery for 10 minutes. If the ABS lamp goes out and the code B1401 does not return - the problem is solved.

⚠️ Attention: If after replacing the sensor and cleaning the contacts the error remains, check the ABS unit for corrosion of the internal tracks. In this case, the unit must be repaired or replaced (the price of a new one is from 15,000 ₽).

Table: Cost of repairs and spare parts to fix B1401

Component	Original (item)	Price, ₽	Analogue (brand)	Price, ₽
ABS sensor (front right)	40520-4M000	2 300–2 800	Febi 25960	1 200–1 500
ABS sensor connector	28460-4M000	800–1 200	Bosch 1 987 340 014	600–900
ABS unit (used, tested)	40500-4M000	8 000–12 000	—	—
ABS wiring harness (repair)	—	—	Automega	1 800–2 500
Diagnostics (service station)	—	1 000–1 500	—	—

Note: Prices are valid for Moscow and the region for the summer of 2026. For regions, the cost may differ by 15–20%. When purchasing a used ABS unit, be sure to check its functionality - often such units are sold with hidden defects.

Common repair mistakes and how to avoid them

Many owners Nissan Almera Classic make typical mistakes when troubleshooting B1401, which leads to code reappearance or new problems. That's what can't do:

• 🚫 Use sensors from other models (for example, from Renault Megane or Nissan Note). Even if the connector is suitable, the characteristics may differ and the ABS unit will generate an error.
• 🚫 Strip wires with a knife - this reduces their cross-section and increases resistance. Use special strippers.
• 🚫 Ignore corrosion on the hub rotor. If the comb is damaged, the new sensor will quickly fail.
• 🚫 Connect the scanner to the diagnostic connector with the ignition on - this may blow the fuse ECU-IG (10A).

Another common mistake is incorrect sensor installation. If the gap between the sensor and the rotor exceeds 1.5mm, the signal will be weak and the error B1401 will return. Check the gap with a feeler gauge or visually (a sheet of paper should pass through, but not a pencil).

What should I do if the error remains after replacing the sensor?

If the new sensor is installed correctly, but B1401 does not disappear, check:

1. **Wiring integrity from the sensor to the ABS unit** (check with a multimeter).

2. **Voltage at the ABS unit connector** (should be ~12V when the ignition is on).

3. **Fuse condition ABS (10A)** in the mounting block.

4. **Correct firmware of the ABS unit** (on some Almera Classic after 2011 a software update is required).

If everything is in order, the problem may be in the ABS unit itself - it needs to be tested on a bench or replaced.

Prevention of error B1401 on Nissan Almera Classic

To avoid reappearance B1401, follow these guidelines:

• 🛡️ Treat ABS sensor connectors silicone grease (for example, Liqui Moly Silicon-Fett) every 30,000 km.
• 🔧 Check the fastening of the wiring harness at each maintenance - it should not hang out or rub against the suspension.
• 🚗 Avoid driving through deep puddles — water gets into the connectors and accelerates corrosion.
• 🔍 Check the condition of the wheel bearings - When replacing them, always check the ABS sensor for damage.

Pay special attention winter operation. Reagents on the roads aggressively corrode contacts, so after heavy snowfalls or thaws it is useful to wash the sensor connectors with water (then dry with compressed air).

FAQ: Frequently asked questions about error B1401

Is it possible to drive with error code B1401 if the brakes work?

Technically yes, but highly undesirable. ABS is disabled, and during emergency braking the wheels may lock, which will increase the braking distance (especially on wet or slippery roads). Also, ignoring the error can lead to failure of the ABS unit - its repair will cost many times more than replacing the sensor.

How to reset error B1401 without a scanner?

Disconnect the negative terminal of the battery for 10-15 minutes. This will clear errors in the ABS unit memory. If the code returns after driving for several kilometers, the problem is not resolved. On some versions Almera Classic (with CAN bus) may require a scanner to perform a full reset.

Will the ABS sensor from Nissan Note fit Almera Classic?

No, despite their external similarity, the sensors have different resistance characteristics and connector shapes. The use of non-original sensors may lead to incorrect operation of the ABS or the appearance of new errors (for example, C1111).

What should I do if the ESP light comes on after replacing the sensor?

This indicates a problem with ABS hydraulic unit or its firmware. Possible reasons:

• Incompatibility of the new sensor with the control unit.
• Damage to the wiring between the ABS unit and the ESP unit.
• ABS pump malfunction (requires diagnostics at a service station).

It is difficult to solve the problem on your own - contact a diagnostician with hydraulic testing equipment.

How much does it cost to repair an ABS unit on an Almera Classic?

The cost depends on the type of fault:

• Cleaning contacts and soldering tracks — 3 000–5 000 ₽.
• Replacing faulty relays or transistors — 6 000–8 000 ₽.
• Complete block replacement (new) - 15,000-20,000 ₽, used - 8,000-12,000 ₽.

Repair is advisable if the unit has no mechanical damage (cracks, traces of impacts).