Diagnosing P2BA700 and P24C600 on a Volvo V60

When a 2018 Volvo V60 rolled in with the check engine light on and codes P2BA700, P24C600, and P24C768, the immediate risk was a no-start condition triggered by a false empty AdBlue tank. The technician wrote “Motorlampa lyser” on the ticket, noting that the check engine light was active. However, the presence of code P2BA700 alongside the particulate matter sensor faults changes the priority of the repair entirely. Code P2BA700 indicates a NOx exceedance due to an empty reagent tank. This code immediately starts a countdown in the engine control module toward a total start prohibition, a hard lockout mandated by emissions legislation. The vehicle was a 2018 Volvo V60 III in the Swedish market, equipped with the 2.0D D4204T14 engine. The technician faced a combination of faults that required immediate attention to prevent the car from stranding the owner.

Tackling the Particulate Sensor Codes P24C600 and P24C768

Codes P24C600 and P24C768 point directly to the particulate matter sensor, specifically isolating a fault in its internal temperature sensor circuit. Our diagnostic platform ranked a defective particulate sensor as the most likely root cause for these specific codes, placing it at an 88 percent probability with a medium severity rating.

On this specific Volvo engine, the particulate matter sensor is mounted directly in the exhaust pipe, positioned downstream of the diesel particulate filter. The sensor operates using an integrated heating element combined with an internal ceramic temperature sensor. Its primary function is to periodically burn off accumulated soot particles from its own measuring element. After the burn off process, it measures new soot accumulation by monitoring changes in electrical resistance.

The failure mechanism for this component is almost entirely environmental and physical. Heavy thermal cycling in the exhaust system, combined with natural component aging, leads to internal cracking. These micro cracks develop in the ceramic material or the measuring element itself. As the damage progresses, the sensor internal temperature probe begins to drift out of specification or completely loses its electrical contact. Once the engine control unit can no longer accurately regulate the sensor working temperature, it registers the failure and sets the fault codes.

Our system provided a very specific diagnostic path for the technician. The first step is to connect a diagnostic tool and read the live data for the particulate sensor temperature and its heater status. The technician must compare these values when the engine is completely cold versus when it is at full operating temperature. The second step involves a careful physical inspection of the sensor probe cable and the connector to rule out visible thermal damage, melting, or a broken wire. Finally, the technician needs to measure the supply voltage at Terminal 15 and verify the ground connection directly at the electronic module of the particulate sensor to confirm the circuit is intact.

The False Empty AdBlue Tank and Code P2BA700

While the particulate sensor requires replacement, the P2BA700 code is the one carrying a high severity rating because it will eventually lock the ignition. Our engine ranked a defective AdBlue level sensor as the second highest probability overall at 78 percent.

The level sensor is integrated directly into the pump and armature module located inside the urea tank. Under normal operation, this sensor measures the fluid level using either ultrasonic waves or resistive tracks. If the sensor suffers an internal circuit fault, if the mechanical float gets stuck, or if an open circuit occurs in the wiring, the component defaults to its lowest value. It reports a permanent empty tank, sending a reading of zero liters or zero percent to the reduction agent control unit. This immediately triggers the P2BA700 code, even when the tank is physically full.

The diagnostic steps here begin with the obvious but critical task of verifying the actual physical liquid level in the AdBlue tank. Once the technician confirms the tank contains fluid, the next step is to read the live data for the AdBlue tank level in the diagnostic tool. The technician must check both the liter reading and the percentage reading, comparing the scanner values with the actual known fill level. If they do not match, the technician moves to checking the voltage supply and the signal connection at the tank armature connector to isolate the electrical side of the circuit. Following any repair or component replacement, a reset and adaptation of the reagent level must be performed.

Urea Crystallization in the Electrical Connectors

There is another highly documented reason for that false empty reading. Our data ranked AdBlue crystallization and moisture intrusion in the tank module connector at a 68 percent probability, carrying a medium severity rating.

The standard 32.5 percent urea solution is notorious for its ability to creep. The slightest micro leak, or even a minor spill around the filler neck and vent connections during routine maintenance, can cause the fluid to migrate. On the Volvo SPA platform, this fluid can penetrate the electrical connector of the tank module or travel along the wiring harness itself.

When the water in the urea solution evaporates, it leaves behind incredibly hard white crystals. These crystals force their way between the contact pins inside the connector. This intrusion creates parasitic currents, isolation faults, and severe pin corrosion. The corrosion alters the resistance values of both the level sensor and the temperature sensor, tricking the control unit into seeing an empty tank.

To diagnose this accurately, the technician must remove and visually inspect the tank module connector. They are looking specifically for white salt crystals and green pin corrosion. It is also necessary to check if urea was spilled at the filler pipe drain and track if it ran down over the electrical connector of the tank. If the connector is contaminated but not destroyed, it must be cleaned thoroughly with warm deionized water, blown completely dry with compressed air, and treated with dielectric contact grease.

Evaluating the SCR Control Unit

Finally, our diagnostic engine assigned a 52 percent probability to a defective selective catalytic reduction control unit, rating it as a high severity fault. This control unit is the brain of the emissions fluid system. It manages the urea dosing, the pressure buildup, and monitors the tank fluid level. It takes the analog and digital signals from the tank level sensor and passes that information to the main engine control module over the CAN bus.

An internal electronic failure within this unit can disrupt the entire system. A failure in the analog to digital converter for the sensor inputs, a fault in the microcontroller, or a problem with the internal voltage regulation can cause the SCR unit to broadcast an empty tank message to the engine control module. This happens even if the physical sensor, the wiring, and the fluid levels are all perfectly fine.

Testing this possibility requires reading the fault memory specifically from the reduction agent control unit itself, rather than just the main engine ECU. The technician should check the CAN bus communication and measure the terminating resistors to ensure the network is intact. The final diagnostic step is to measure for a stable supply voltage and a solid ground connection directly at the reduction agent control unit while the system is under load.

Next Steps in the Bay

Tracking down overlapping emissions faults requires a disciplined testing sequence to avoid replacing expensive modules unnecessarily. Do you frequently see this combination of particulate sensor degradation and false AdBlue lockouts on the Volvo SPA platform in your workshop?