P205C – Reductant Tank Level Sensor Circuit Low

What is Code P205C?

OBD-II diagnostic trouble code (DTC) P205C stands for "Reductant Tank Temperature Sensor Circuit Low". This is a generic powertrain code that applies to diesel vehicles equipped with a Selective Catalytic Reduction (SCR) system, which is an emissions control system that uses Diesel Exhaust Fluid (DEF).

The code indicates that the powertrain control module (PCM) has detected an insufficient voltage in the reductant tank temperature sensor circuit. In other words, the PCM sees the temperature sensor signal voltage is below the acceptable range.

Urgency and Severity

A stored P205C code should be considered a severe issue and diagnosed as soon as possible. Driving with this code active is not recommended, as it can cause the SCR system to become disabled which may lead to damage to the catalytic converter if the underlying problem is not fixed promptly.

While it may be okay to drive short distances to a repair shop, continuing a long road trip with the check engine light on and code P205C present is inadvisable. Doing so risks more extensive and expensive damage. If the code appears, the safest approach is to have the vehicle towed to a qualified repair facility for proper diagnosis.

Vehicles Affected

Code P205C is a generic code that can appear on any modern diesel vehicle with an SCR system, including but not limited to:

• Ford Power Stroke
• Dodge/Ram Cummins
• Chevy/GMC Duramax
• Mercedes-Benz BlueTEC
• BMW diesels
• Audi/Volkswagen TDI

The exact repair steps and part numbers will vary by make and model. Always refer to manufacturer service information for the specific vehicle when diagnosing and repairing this code.

Parts Involved

The main components related to code P205C are:

1. Reductant tank (also called the DEF tank) – Stores the diesel exhaust fluid
2. Reductant tank temperature sensor – Measures the temperature of the DEF
3. Reductant tank heater – Warms the DEF in cold conditions to prevent freezing
4. Wiring and connectors – Carries the temperature sensor signal to the PCM

Role of the Parts

The reductant tank temperature sensor monitors the temperature of the DEF. The PCM uses this input to control the tank heater and ensure the DEF stays in the proper temperature range, typically between 12-86°F (-11-30°C). If the DEF gets too cold, it can freeze and cause issues with the SCR system.

Common Causes

Some of the most common causes of a P205C code include:

• Faulty reductant tank temperature sensor
• Damaged wiring or loose/corroded connector at the sensor
• Malfunctioning reductant tank heater
• Contaminated or degraded DEF fluid
• In rare cases, a problem with the PCM

Diagnosis Steps

1. Connect a scan tool and verify the P205C code is present. Check for any other codes which may help pinpoint the issue.

2. Visually inspect the wiring and connector at the reductant tank temperature sensor. Repair any obvious damage.

3. With the key off, unplug the sensor and check for voltage between the power and ground wires per manufacturer specs, typically 4.8-5.2 V. If voltage is out of spec, trace the circuit for faults.

4. Check the resistance of the temperature sensor itself at ambient temperature and compare to manufacturer specs. Replace the sensor if out of range.

5. If the wiring and sensor test okay, the problem may be with the reductant tank heater. Further diagnosis with a scan tool to command the heater on and test heater resistance will be needed.

6. As a final step, evaluate the condition and concentration of the DEF using a refractometer. The DEF should be clear and have a concentration between 31.8-33.2%. Replace if contaminated or degraded.

Repair Solutions

After completing the diagnosis, the most likely repair will be one of the following:

• Replacing the reductant tank temperature sensor
• Repairing damaged wiring or connectors
• Replacing the reductant tank heater assembly
• Draining and refilling the reductant tank with fresh DEF fluid

In very rare instances, a faulty PCM may need reprogramming or replacement, but this should only be considered after ruling out all other possibilities.

Prevention

To help prevent a P205C code from reoccurring:

• Only use high-quality DEF fluid from a reputable supplier
• Avoid storing DEF for longer than 12 months as it degrades over time
• If the DEF freezes due to extreme cold, allow time for it to thaw naturally – never add any other substances to the tank
• Address any leaks from the reductant tank or delivery system promptly
• Maintain the rest of the emissions system properly to avoid excess soot which can contaminate the DEF

Repair Cost

The cost to repair a P205C code will depend on the root cause but will typically range from $150-$600. Some common repair costs:

• Reductant temperature sensor: $80-$200
• Reductant tank heater assembly: $400-$600
• DEF fluid: $8-$20 per gallon ($2-$5 per liter)
• Wiring repairs: $100-$300 depending on extent of damage

Note that these are general estimates and actual costs can vary significantly depending on vehicle make, model, and location. Always get a detailed estimate from a trusted repair shop before proceeding with any repairs.

Related Faults

Some other fault codes that may appear along with or related to P205C include:

• P20EE – SCR NOx Catalyst Efficiency Below Threshold
• P2BAE – Reductant Heater "A" Control Circuit/Open
• P20E8 – Reductant Pressure Too Low
• P2BAF – Reductant Tank Temperature Sensor "A" Circuit High

Seeing multiple codes together can help point to the root cause more quickly. For example, a P2BAE code along with P205C strongly suggests an issue with the reductant heater circuit.

In conclusion, code P205C indicates a problem with the reductant tank temperature sensor circuit which can disable the SCR system if not addressed promptly. Proper diagnosis is critical to avoid unnecessary repairs and prevent catalyst damage. If you are not confident tackling this issue yourself, seek help from a professional technician experienced with modern diesel emission systems.

Frequently Asked Questions About P205C

What does the P205C code mean?

P205C stands for “Reductant Tank Temperature Sensor Circuit Low.” It indicates the powertrain control module has detected a low voltage condition in the diesel exhaust fluid (DEF) tank temperature sensor circuit.

How urgent is it to address a P205C code?

This code should be considered severe and addressed as soon as possible. Driving long distances with this code active is not recommended, as it can disable the SCR system and potentially damage the catalytic converter.

Can I continue driving with a P205C code?

While you may be able to drive short distances to a repair shop, it’s not advisable to continue normal driving. The safest approach is to have the vehicle towed to a qualified repair facility.

What vehicles commonly experience the P205C code?

This code can appear on any modern diesel vehicle with a Selective Catalytic Reduction (SCR) system, including Ford, Dodge/Ram, Chevy/GMC, Mercedes-Benz, BMW, and Volkswagen diesel models.

What are the main components involved with a P205C code?

The key components are the reductant (DEF) tank, reductant tank temperature sensor, reductant tank heater, and associated wiring and connectors.

What is the role of the reductant tank temperature sensor?

This sensor monitors the temperature of the DEF fluid. The PCM uses this input to control the tank heater and ensure the DEF stays within the proper temperature range, typically between 12-86°F (-11-30°C).

What are common causes of a P205C code?

Common causes include a faulty reductant tank temperature sensor, damaged wiring or connectors, a malfunctioning reductant tank heater, contaminated DEF fluid, or rarely, a PCM issue.

How is a P205C code diagnosed?

Diagnosis typically involves scanning for codes, visually inspecting wiring and connectors, testing voltage and resistance in the sensor circuit, and evaluating the DEF fluid condition.

What tools are needed to diagnose a P205C code?

A diagnostic scanner, digital multimeter, and possibly a refractometer for testing DEF concentration are typically required.

What are the potential repair solutions for a P205C code?

Common repairs include replacing the reductant tank temperature sensor, repairing wiring or connectors, replacing the reductant tank heater assembly, or replacing contaminated DEF fluid.

How can I prevent a P205C code from occurring?

Use high-quality DEF fluid, avoid storing DEF for extended periods, address any system leaks promptly, and maintain the emissions system properly.

What is the typical cost range for repairing a P205C code?

Repair costs typically range from $150-$600, depending on the root cause and specific vehicle model.

Are there any related fault codes to P205C?

Yes, related codes may include P20EE, P2BAE, P20E8, and P2BAF, which are all associated with the SCR system.

Can a P205C code cause damage to my vehicle if left unaddressed?

Yes, ignoring this code can potentially lead to damage to the catalytic converter and other components of the emissions system.

Is the P205C code covered under emissions warranties?

In many cases, yes. This code is related to the emissions system, which is often covered under extended emissions warranties. Check with your vehicle manufacturer for specifics.

How long does it typically take to repair a P205C code?

Repair time can vary depending on the root cause, but typically ranges from 1-3 hours for most repairs.

Can I clear the P205C code myself?

While you can clear the code with a scan tool, it will likely return if the underlying issue isn’t addressed. It’s best to have the problem properly diagnosed and repaired.

Will a P205C code cause my vehicle to fail an emissions test?

Yes, in most cases an active P205C code will cause a vehicle to fail an emissions test.

Can extreme cold weather contribute to a P205C code?

Yes, very cold temperatures can cause DEF to freeze, which may trigger this code if the tank heater isn’t functioning properly.

Is it safe to add additives to my DEF tank to prevent freezing?

No, never add any substances other than approved DEF to the reductant tank. This can cause severe damage to the SCR system.