P205A – Reductant Tank Level Sensor Circuit

Urgency and Driving Considerations

A stored code P205A is considered severe and should be addressed promptly. Continuing to drive with this code active could disable the Selective Catalytic Reduction (SCR) system, potentially leading to catalyst damage. It is recommended to diagnose and repair the issue as soon as possible, ideally by visiting a qualified mechanic or dealer.

Code Details

P205A is a generic powertrain code applicable to many OBD-II vehicles (1996 and newer), including Mercedes, Sprinter, Ford, GMC, and Chevrolet. While the code is generic, specific repair steps may vary depending on the vehicle's year, make, model, and powertrain configuration.

The code indicates that the powertrain control module (PCM) has detected an abnormal voltage level in the reductant tank temperature sensor circuit. Multiple ignition cycles with a failure may be required for the malfunction indicator lamp (MIL) to illuminate.

Parts Involved

The main component in question is the reductant tank temperature sensor, a variable resistor used to measure the temperature inside the reductant tank. The reductant, often diesel exhaust fluid (DEF), is a critical part of the SCR system, which reduces nitrogen oxide (NOx) emissions in diesel vehicles.

Common Causes

Possible causes for a P205A code include:

• Defective reductant tank temperature sensor
• Wiring issues in the reductant tank temperature sensor circuit (e.g., damaged wires, poor connections)
• Faulty PCM or SCR controller

Diagnosing Steps

1. Use a diagnostic scanner to retrieve all stored codes and relevant freeze frame data.
2. Consult vehicle-specific diagnostic information, such as technical service bulletins (TSBs), for helpful insights.
3. Test the reductant temperature sensor using a digital volt/ohmmeter (DVOM) according to the manufacturer's specifications.
4. If the sensor is functioning correctly, use the DVOM to test the input and output signal circuits between the temperature sensor and the PCM/SCR controller.

Solutions and Prevention

Depending on the diagnosis, solutions may include:

• Replacing the reductant tank temperature sensor
• Repairing or replacing damaged wiring in the sensor circuit
• Updating the PCM or SCR controller software, if applicable
• Replacing the PCM or SCR controller, if faulty

To prevent reoccurrence, ensure proper maintenance of the SCR system, including regular DEF refills with high-quality fluid and addressing any leaks or damage promptly.

Repair Costs

The cost of repairing a P205A code can vary depending on the specific issue and vehicle. On average, expect to pay:

• Reductant tank temperature sensor: $100-$300 (€85-€255)
• Wiring repairs: $50-$200 (€43-€170)
• PCM or SCR controller replacement: $500-$1,500 (€425-€1,275)

Labor costs can range from $75 to $150 (€64 to €128) per hour, with diagnosis and repair typically taking 1-4 hours.

Related Issues and Fault Codes

Other fault codes that may appear alongside P205A include:

• P20EE: SCR NOx Catalyst Efficiency Below Threshold
• P2BAE: Reductant Pressure Too Low
• P20E8: Reductant Pressure Too High
• P2BAF: Reductant Tank Temperature Sensor Circuit Range/Performance

These codes suggest issues with the SCR system, which should be addressed comprehensively to ensure proper emission control and vehicle performance.

Frequently Asked Questions About P205A

What does the OBD-II code P205A mean?

P205A is a generic powertrain code that indicates the powertrain control module (PCM) has detected an abnormal voltage level in the reductant tank temperature sensor circuit.

What are the common symptoms of code P205A?

Common symptoms include:

• Check engine light illumination
• Reduced engine performance
• Decreased fuel efficiency
• Excessive black exhaust smoke during acceleration

How severe is code P205A?

P205A is considered a severe code that should be addressed promptly. Ignoring it could disable the Selective Catalytic Reduction (SCR) system and potentially cause catalyst damage.

What are the possible causes of code P205A?

Possible causes include:

• Defective reductant tank temperature sensor
• Wiring issues in the sensor circuit (e.g., damaged wires, poor connections)
• Faulty PCM or SCR controller

What parts are involved with code P205A?

The main part involved is the reductant tank temperature sensor, which measures the temperature inside the diesel exhaust fluid (DEF) tank. The DEF is a critical component of the SCR system.

What tools are needed to diagnose code P205A?

To properly diagnose P205A, you will need:

• An OBD-II scanner to retrieve codes and freeze frame data
• A digital volt/ohmmeter (DVOM) for testing
• Vehicle-specific diagnostic information (e.g., wiring diagrams, specifications)

What are the basic steps to diagnose code P205A?

The basic diagnostic steps are:

1. Retrieve codes and freeze frame data with a scanner
2. Consult vehicle-specific information for insights
3. Test the reductant temperature sensor with a DVOM
4. If the sensor tests okay, use the DVOM to check the sensor’s input and output signal circuits

How can I fix code P205A?

Fixes for P205A may include:

• Replacing the reductant tank temperature sensor
• Repairing damaged wiring in the sensor circuit
• Updating the PCM or SCR controller software
• Replacing a faulty PCM or SCR controller

Can I continue driving with code P205A?

It is not recommended to keep driving with P205A active. Doing so risks disabling the SCR system and potentially damaging the catalytic converter. The issue should be diagnosed and repaired as soon as possible.

How much does it typically cost to repair code P205A?

Repair costs for P205A can vary but may range from $100-$300 for a new reductant tank temperature sensor, $50-$200 for wiring repairs, or $500-$1500 for a PCM/SCR controller replacement. Labor is additional.

Can low-quality DEF cause code P205A?

While low-quality DEF is unlikely to directly cause P205A, it can lead to other issues with the SCR system that may eventually trigger this code. It’s best to use high-quality DEF from reputable sources.

How often should the reductant tank temperature sensor be replaced?

There is no specific replacement interval for this sensor. It should be replaced if testing determines it has failed or as part of repairing P205A if the sensor is faulty.

Can a malfunctioning reductant tank heater cause code P205A?

Yes, a faulty reductant tank heater could cause the DEF temperature to be out of range, potentially triggering code P205A.

Is code P205A specific to diesel vehicles?

Yes, P205A is primarily found on diesel vehicles equipped with Selective Catalytic Reduction (SCR) systems to control NOx emissions.

Can a software update fix code P205A?

In some cases, a software update for the PCM or SCR controller may resolve P205A, especially if the code is triggered by a programming issue rather than a hardware problem. However, any underlying hardware faults must still be addressed.

What other codes may appear along with P205A?

Related codes that may appear with P205A include:

• P20EE: SCR NOx Catalyst Efficiency Below Threshold
• P2BAE: Reductant Pressure Too Low
• P20E8: Reductant Pressure Too High
• P2BAF: Reductant Tank Temperature Sensor Circuit Range/Performance

Can a blocked DEF injector cause code P205A?

A blocked DEF injector is more likely to cause codes related to reductant pressure or SCR efficiency than P205A, which deals specifically with the reductant tank temperature sensor circuit.

How does the reductant tank temperature sensor work?

The reductant tank temperature sensor is a thermistor that changes resistance based on DEF temperature. The PCM supplies a reference voltage to the sensor and monitors the return voltage to determine temperature.

Can code P205A cause a vehicle to fail an emissions test?

Yes, an active P205A code can cause a vehicle to fail an OBD-II based emissions test. The code must be repaired and the readiness monitors reset before retesting.

Is it safe to use an aftermarket reductant tank temperature sensor?

While aftermarket sensors can be less expensive, it is generally recommended to use an OEM or OEM-equivalent sensor to ensure proper fit, function, and durability. Saving money is not worth risking further SCR system issues.