Diagnostic Protocol for Intermittent Faults in the Fuel Pump Relay and Crankshaft Position Sensor of the Sandero Stepway

The Problem: The engine cranks powerfully, but the car won’t start.

One of the most frustrating situations for a Renault Sandero Stepway owner is trying to start the car and realizing that the starter motor turns normally, but the vehicle won’t start. This symptom indicates that the battery is healthy and the starting system is sending power to the engine, however, some essential element for combustion is missing: either the fuel is not reaching the injectors, or there is no spark at the spark plugs.

In the Sandero, this scenario usually points to two main culprits that tend to exhibit intermittent faults (those that occur out of nowhere and sometimes disappear on their own): the fuel pump relay and the rotation sensor. This article details how to identify and resolve these vulnerabilities in a technical and safe manner.

Probable Causes: Understanding the Components

For the engine to work, the ECU (Electronic Control Unit) You need to know the exact position of the pistons and allow the flow of energy and fuel. If either of these paths is blocked, the car “spins its wheels”.

1. The Rotation Sensor (CKP Sensor)

The crankshaft position sensor is a magnetic component usually located near the engine flywheel. Its function is to inform the engine control unit (ECU) that the engine is rotating. If it fails, the ECU does not send the command to the ignition coils to generate a spark. In Renault models, it is common for iron filings to accumulate on the tip of the sensor or for there to be poor contact in its electrical connector.

2. The Fuel Pump Relay

The relay functions like an automatic electrical switch. When you turn the key, the control unit closes this switch to power the fuel pump in the tank. If the relay’s internal contacts are worn or oxidized, the pump does not receive power, and the engine does not receive gasoline or ethanol to burn.

Common Fault Codes (DTCs)

When connecting an automotive scanner to the OBD2 port (diagnostic input located in the glove compartment or center console), you may encounter the following. DTCs (fault codes registered by the electronic injection system):

• P0335: Malfunction in the crankshaft position sensor circuit (the rotation sensor).
• P0230: Fuel pump primary circuit fault (indicates problems with the relay or wiring).
• P0627: Fuel pump control circuit is open.

Step-by-Step Diagnosis

To identify which part is failing in your Sandero Stepway, follow this verification protocol:

Step 1: Hearing Test

Ask someone to turn the key to the “ignition” position (without starting the engine) while you listen near the back seat. You should hear a low humming sound for about 2 seconds. If you don’t hear anything, the problem is probably with the ignition. relay or in itself pump.

Step 2: Fuse Box Inspection

Open the fuse box located in the engine compartment (next to the battery). The fuel pump relay in the Sandero is usually a small cube, generally black or brown. Check for signs of melting or oxidized (greenish) pins. A simple test is to swap the fuel pump relay with the horn or air conditioning relay, if they are identical, to see if the car starts again.

Step 3: Cleaning the Rotation Sensor

If the fuel pump hum is present, the focus shifts to the crankshaft position sensor. It is secured by two screws (usually 10mm) at the junction between the engine and the transmission. Remove it and clean the magnetic tip with a clean cloth. If there is too much dirt, this prevents an accurate reading.

Location and Electrical References

In the Sandero Stepway, the electrical system configuration may vary depending on the year (Generation 1 or 2), but the standard values ​​are:

Solutions and Spare Parts

If the fault is confirmed, replacement is the safest way to avoid being stranded on the road again.

• Relay Replacement: It’s the cheapest solution. Use parts from reputable brands or genuine Renault parts. Avoid unbranded relays, as incorrect internal resistance can damage the control unit.
• Replacing the Rotation Sensor: Often, simply cleaning the sensor won’t solve the problem if it’s internal. When buying a new one, check if the connector is the old (square) or new (rounded) model.
• Whip Kit: In many Sandero cases, the problem isn’t the sensor itself, but the plug that connects to it. There are wiring harness repair kits that permanently fix the bad connection.

Approximate Costs in Brazil

Prices may vary depending on the region and the chosen workshop, but on average:

• Pump Relay: Between R$30.00 and R$80.00.
• Rotation Sensor: Between R$120.00 and R$280.00 (new item).
• Labor: Diagnosis and replacement usually range from R$150.00 to R$350.00 in independent workshops.

A visit to the dealership is recommended if the vehicle is under warranty or if the problem is in the main wiring harness, where diagnosis requires specific equipment from the manufacturer.

Prevention and Final Tips

To prevent your Sandero Stepway from suffering from these intermittent failures, keep up with preventive maintenance. Avoid constantly driving with the fuel tank on reserve, as this overloads the pump and relay due to excessive heat. Additionally, during 40,000 km services, ask your mechanic to check the condition of the electrical connectors in the engine compartment, applying an appropriate contact cleaner spray to prevent oxidation.

Remember: if the car cranks but doesn’t start, and the check engine light flashes or stays on, don’t insist on starting it too much to avoid draining the battery or damaging the catalytic converter with unburned fuel.

Disclaimer

This article is for informational and reference purposes only. The content published here was compiled from publicly available technical information and general market references, and does not, under any circumstances, replace the diagnosis and intervention of a qualified mechanic or authorized dealership. The website is not responsible for any damages, losses, or consequences arising from the practical application of the guidelines described here. Always confirm part codes, torques, and procedures in the manufacturer’s official manual before any repair.