How serious is this DTC?

When a P2346 is stored, the cause must be diagnosed as soon as possible. The symptoms contributing to the storage of this type of code can range from minimal to catastrophic.

What are some of the symptoms of the code?

Symptoms of a P2346 trouble code may include:

• Engine noise
• Decreased engine performance
• Reduced fuel efficiency
• Other related codes
• There may be no distinctive symptoms

What are some common causes of the code?

Causes of this code may include:

• Faulty knock sensor
• Engine malfunction or incorrect fuel type
• Open or shorted wiring or wiring connectors
• Engine noise caused by component failure
• PCM or programming error

What are the P2346 troubleshooting steps?

Ensure the engine is filled to the appropriate level with the correct oil and is in good working condition. Actual engine noises, such as spark knock, must be eliminated before a P2346 diagnosis can be made.

You will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable source of vehicle information to accurately diagnose a P2346 code.

You can save time and trouble by searching for Technical Service Bulletins (TSBs) that match the stored code, the vehicle (year, make, model, and engine), and the symptoms presented. This information can be found in your vehicle information source. If you find the right TSB, it might provide a quick solution to your diagnosis.

After connecting the scanner to the vehicle’s diagnostic port and retrieving all stored codes and relevant freeze frame data, note the information (in case the code turns out to be intermittent). After that, clear the codes and test the vehicle until one of two things happens; the code is restored or the PCM enters readiness mode.

The code may be more difficult to diagnose if the PCM enters readiness mode at this point, as the code is intermittent. The condition that caused the P2346 to be stored may need to worsen before an accurate diagnosis can be made. If the code is restored, proceed with the diagnosis.

You can obtain connector face views, connector pinout diagrams, component location charts, wiring diagrams, and diagnostic flowcharts (related to the code and the vehicle in question) using your vehicle information source.

Perform a visual inspection of the associated wiring and connectors. Repair or replace wiring that is cut, burned, or damaged. Scheduled maintenance includes replacing spark plug wires and boots. If the vehicle in question is beyond the recommended maintenance interval for a tune-up, suspect faulty spark plug wires/boots as the cause of a stored P2346.

After disconnecting the PCM, use the DVOM to check continuity in the knock sensor circuit. Since the knock sensor is usually screwed into the engine block, be careful not to burn yourself with coolant or oil when removing the sensor. Test continuity through the sensor and back to the PCM connector.

The P2346 code can usually be attributed to a PCM programming error, a faulty knock sensor, or engine knock.

How serious is this DTC?

When a P2347 is stored, the cause must be diagnosed as soon as possible. The symptoms contributing to the storage of this type of code can range from minimal to catastrophic.

What are some of the symptoms of the code?

Symptoms of a P2347 trouble code may include:

• Engine noise
• Decreased engine performance
• Reduced fuel efficiency
• Other related codes
• There may be no distinctive symptoms

What are some common causes of the code?

Causes

of this code may include:

• Faulty knock sensor
• Engine failure or incorrect fuel type
• Open or shorted wiring or wiring connectors
• Engine noise caused by component failure
• PCM or programming error

What are the P2347 troubleshooting steps?

Ensure the engine is filled to the appropriate level with the correct oil and is in good working condition. Actual engine noise, such as knocking, must be eliminated before a P2347 diagnosis can be made.

You will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable source of vehicle information to accurately diagnose a P2347 code.

You can save time and trouble by searching for Technical Service Bulletins (TSBs) that match the stored code, the vehicle (year, make, model, and engine), and the symptoms presented. This information can be found in your vehicle information source. If you find the right TSB, it might provide a quick solution to your diagnosis.

After connecting the scanner to the vehicle’s diagnostic port and retrieving all stored codes and relevant freeze frame data, note the information (in case the code turns out to be intermittent). After that, clear the codes and test the vehicle until one of two things happens; the code is restored or the PCM enters readiness mode.

The code may be more difficult to diagnose if the PCM enters readiness mode at this point, as the code is intermittent. The condition that caused the P2347 to be stored may need to worsen before an accurate diagnosis can be made. If the code is restored, proceed with the diagnosis.

You can obtain connector face views, connector pinout diagrams, component location charts, wiring diagrams, and diagnostic flowcharts (related to the code and the vehicle in question) using your vehicle information source.

Perform a visual inspection of the wiring and associated connectors. Repair or replace wiring that has been cut, burned, or damaged. Scheduled maintenance includes replacing wires and spark plug boots. If the vehicle in question is beyond the recommended maintenance interval for a tune-up, suspect faulty ignition wires/spark plug boots as the cause of a stored P2347.

After disconnecting the PCM, use the DVOM to check continuity in the knock sensor circuit. Since the knock sensor is usually screwed into the engine block, be careful not to burn yourself with coolant or oil when removing the sensor. Test continuity through the sensor and back to the PCM connector.

The P2347 code can usually be attributed to a PCM programming error, a faulty knock sensor, or engine knocking.

How severe is this DTC?

Most of the time, I would say that emission-related codes are fairly low on the severity scale. Especially when compared to some potential dangers in other vehicle systems like steering, suspension, brakes, etc. The point here is that if you have bigger fish to fry, so to speak, you can put it on the back burner for now. That said, any electrical fault should be treated with a certain sense of urgency.

What are some of the symptoms of the code?

Symptoms of a P2200 fault code may include:

• Increased hydrocarbon emissions
• Check engine light on
• Inconsistent fuel economy
• Irregular idle
• Excessive smoke

What are some common causes of the code?

Causes

of this P2200 fuel compensation code may include:

• Faulty or damaged NOx sensor
• Dirty sensor
• Damaged wiring
• Internal ECM problem
• Connector issue

What are the troubleshooting steps for P2200?

Visually inspect your sensor and harness. Sometimes, the elements in which we expose our vehicles are the very reason for your fault. I’ve seen rocks, curbs, snow, and ice remove sensors like these, so make sure the sensor is intact and looks good. Keep in mind that some of these harnesses may be routed in close proximity to the exhaust, so it’s possible for wires to be burned/melted and cause all sorts of problems.

TIP: Let the engine cool down before working near the exhaust.

Clean the sensor. Ensure that any sensor mounted in the exhaust goes through countless heating and cooling cycles. Therefore, they expand and contract enough to sometimes seize in the sensor’s “bung” (threaded hole) on the exhaust.

If that’s the case, you may need to apply heat to the threads, NOT directly to the sensor, as you risk damaging the NOx sensor that way. If you’ve never applied heat to help break free nuts or bolts, I advise against starting with this. That being said, if you have doubts about your skills/abilities, you should always take your vehicle to a reputable service station.

How serious is this DTC?

Most of the time, I would say that emission-related codes are fairly low on the severity scale. Especially when compared to some potential dangers in other vehicle systems like steering, suspension, brakes, etc. The point here is that if you have bigger fish to fry, so to speak, you can put it on the back burner for now. That said, any electrical fault should be treated with a certain sense of urgency.

What are some of the symptoms of the code?

Symptoms of a P2201 fault code may include:

• Increased hydrocarbon emissions
• Check engine light on
• Inconsistent fuel economy
• Irregular idle
• Excessive smoke

What are some common causes of the code?

Causes

of this P2201 fuel compensation code may include:

• Faulty or damaged NOx sensor
• Dirty sensor
• Damaged wiring
• Internal ECM problem
• Connector issue

What are the troubleshooting steps for P2201?

Visually inspect your sensor and harness. Sometimes, the elements in which we expose our vehicles are the very reason for your fault. I’ve seen rocks, curbs, snow, and ice remove sensors like these, so make sure the sensor is intact and looks good. Keep in mind that some of these harnesses may be routed in close proximity to the exhaust, so it’s possible that the wires are burned/melted and causing all sorts of problems.

TIP: Let the engine cool down before working near the exhaust.

Clean the sensor. Ensure that any sensor mounted in the exhaust goes through countless heating and cooling cycles. Therefore, they expand and contract enough to sometimes become stuck in the sensor’s “bung” (threaded hole) on the exhaust.

If that’s the case, you may need to apply heat to the threads, NOT directly to the sensor, as you risk damaging the NOx sensor that way. If you’ve never applied heat to help break free nuts or bolts, I advise against starting with this. That being said, if you have doubts about your skills/abilities, you should always take your vehicle to a reputable service station.

How severe is this DTC?

Most of the time, I would say that emission-related codes will be fairly low on the severity scale. Especially when compared to some potential hazards in other vehicle systems like steering, suspension, brakes, etc. The point here is that if you have bigger fish to fry, so to speak, you can put it on the back burner for now. That said, any electrical fault should be treated with a certain sense of urgency.

What are some symptoms of the code?

Symptoms of a P2202 fault code may include:

• Increased hydrocarbon emissions
• Check engine light on
• Inconsistent fuel economy
• Rough idle
• Excessive smoke

What are some common causes of the code?

Causes

of this P2202 fuel compensation code may include:

• Faulty or damaged NOx sensor
• Dirty sensor
• Damaged wiring
• Internal ECM problem
• Connector issue

What are the P2202 troubleshooting steps?

Visually inspect your sensor and harness. Sometimes, the elements in which we expose our vehicles are the very reason for your fault. I’ve seen rocks, curbs, snow, and ice remove sensors like these, so make sure the sensor is intact and looks good. Keep in mind that some of these harnesses may be routed in close proximity to the exhaust, so it’s possible that the wires are burned/melted and causing all sorts of problems.

TIP: Let the engine cool down before working near the exhaust.

Clean the sensor. Ensure that any sensor mounted in the exhaust goes through countless heating and cooling cycles. Therefore, they expand and contract enough to sometimes become stuck in the sensor “bung” (threaded hole) on the exhaust.

If that’s the case, you may need to apply heat to the threads, NOT directly to the sensor, as you risk damaging the NOx sensor that way. If you’ve never applied heat to help break free nuts or bolts, I advise against starting with this. That being said, if you have doubts about your skills/abilities, you should always take your vehicle to a reputable service station.

How severe is this DTC?

Most of the time, I would say that emission-related codes are fairly low on the severity scale. Especially when compared to some potential dangers in other vehicle systems like steering, suspension, brakes, etc. The point here is that if you have bigger fish to fry, so to speak, you can put it on the back burner for now. That said, any electrical fault should be treated with a certain sense of urgency.

What are some of the symptoms of the code?

Symptoms of a P2203 fault code may include:

• Increased hydrocarbon emissions
• Check engine light on
• Inconsistent fuel economy
• Rough idle
• Excessive smoke

What are some common causes of the code?

Causes

of this P2203 fuel compensation code may include:

• Faulty or damaged NOx sensor
• Dirty sensor
• Damaged wiring
• Internal ECM problem
• Connector issue

What are the troubleshooting steps for P2203?

Visually inspect your sensor and harness. Sometimes, the elements we expose our vehicles to are the very reason for your fault. I’ve seen rocks, curbs, snow, and ice remove sensors like these, so make sure the sensor is intact and looks good. Keep in mind that some of these harnesses may be routed in close proximity to the exhaust, so it’s possible for wires to be burned/melted and cause all sorts of problems.

TIP: Let the engine cool down before working near the exhaust.

Clean the sensor. Ensure that any sensor mounted in the exhaust goes through countless heating and cooling cycles. Therefore, they expand and contract enough to sometimes become seized in the sensor “bung” (threaded hole) on the exhaust.

If that’s the case, you may need to apply heat to the threads, NOT directly to the sensor, as you risk damaging the NOx sensor that way. If you’ve never applied heat to help break free nuts or bolts, I advise against starting with this. That being said, if you have any doubts about your skills/abilities, you should always take your vehicle to a reputable service station.

🚨 Code P2204: Severity, Symptoms, and Solutions for a Faulty NOx Sensor
⚠️ Code P2204 Severity: Medium

Urgency Level: 🔸 Orange (Address within 1 to 2 weeks).

• Immediate Impact: No direct safety danger, but risk of increased pollutant emissions and catalyst degradation.
• Secondary Risks:
• Increased fuel consumption (up to +15%).
• Blockage of DPF (Diesel Particulate Filter) regeneration in diesel vehicles.
• Can I drive? Yes, but avoid long trips.

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🔍 Symptoms of Code P2204

• Check Engine Light On ⚠️.
• High emissions of hydrocarbons (HC) and nitrogen oxides (NOx).
• Unstable idle or abnormal vibrations.
• Black/white smoke from the exhaust.
• Decreased engine performance (limp mode).

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🛠️ Common Causes of Code P2204

1. Faulty NOx Sensor: Wear, soot contamination, or overheating.
2. Damaged Wiring: Cut wires, oxidized or burnt connectors near the exhaust.
3. ECM Problem (Engine Control Module): Outdated software or hardware failure.
4. Sensor Fouling: Accumulation of particles or carbon deposits.

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🔧 Troubleshooting Steps for Code P2204

1. Visual Inspection of the NOx Sensor and Wiring

• Locate the sensor (usually near the catalyst or DPF).
• Check for cracks, corrosion, or exposed wires.
• 🔥 Tip: Let the engine cool before touching the exhaust!

2. Cleaning the NOx Sensor

• Use a specialized sensor cleaner (avoid water or harsh solvents).
• Gently brush off carbon deposits.

3. Testing the Electrical Circuit

• Measure resistance and voltage with a multimeter.
• Expected values:
• Resistance: 100–500 Ω (depending on model).
• Voltage: 0.1–4.5 V (when cold).

4. Checking the ECM

• Use an OBD2 scanner to check for related codes (e.g., P2200, P2201).
• Update the ECM software if necessary.

5. Replacing the NOx Sensor (if necessary)

• Average cost: €150–400 (depending on vehicle).
• 🔧 Tip: Apply a penetrating oil to the threads before removal to prevent breakage.

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📋 Estimated Repair Costs

Service	Cost (€)
Sensor cleaning	50–100
NOx sensor replacement	150–400
Wiring repair	80–200
ECM diagnostic	60–120

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❓ FAQ: Frequently Asked Questions

Q: Can I ignore code P2204?
→ A: No! It can damage the catalyst or DPF, costing up to €2,000 in repairs.

Q: Can code P2204 clear by itself?
→ A: Only if the fault is intermittent (e.g., temporary bad connection).

Q: How long to repair a P2204 code?
→ A: Between 1 hour (cleaning) and 3 hours (sensor replacement + reprogramming).

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🚗 Conclusion: Act Quickly to Avoid Major Damage

An unresolved P2204 code can lead to:

• Costly repairs (DPF, catalyst).
• Failure in technical inspection.
• Increased pollution.

⚠️ Pro Tip: Use an exhaust system additive to reduce sensor fouling.

How severe is this DTC?

Moderate severity for this, as emission-related faults can truly affect the surrounding environment. That said, sometimes with emission faults, there will be no symptoms present but can still have repercussions if left unaddressed.

What are some of the symptoms of the code?

Symptoms of a P2205 diagnostic code may include:

• Failed emissions test
• Intermittent CEL (Check Engine Light)

What are some common causes of the code?

Causes

of this P2205 cruise control code may include:

• Faulty NOx sensor
• Defective NOx sensor heater
• Internal open in the ECM (Engine Control Module) or the NOx sensor itself
• Water intrusion
• Broken connector tabs (intermittent connection)
• Melted harness
• Dirty sensor element
• High resistance present in the heater control circuit

What are the diagnostic and troubleshooting steps for P2205?

The first step in the troubleshooting process for any malfunction is to check Technical Service Bulletins (TSBs) for known issues with the specific vehicle.

Advanced diagnostic steps become very vehicle-specific and may require the appropriate advanced equipment and knowledge to operate accurately. We include the basic steps below but refer to a repair guide specific to the year/make/model/drivetrain for steps tailored to your vehicle.

Basic Step #1

Most NOx sensors used in automotive and diesel truck applications will be fairly accessible. Given this fact, keep in mind that they can be extremely stubborn to remove due to all the expansion and contraction that occurs with temperature fluctuations in the exhaust system. So, make sure you need to remove the sensor before doing so. Most sensor tests should be able to be performed from the connector. Refer to your service manual for pinpoint testing of the NOx sensor to obtain the desired values.

NOTE: You may need to use some heat when replacing the NOx sensor to avoid stripping the threads of the exhaust plug. Penetrating oil is always a good idea whenever you think you might remove the sensor in the near future.

Basic Step #2

Follow the harness involved with the NOx sensor to assess its condition. Most of the time, harnesses will be routed near the extreme heats mentioned earlier. So, keep a close eye out for melted harnesses or connectors. Be sure to repair any chafing or damaged harnesses to prevent future malfunctions.

Basic Step #3

Visually inspect the exhaust system, especially the interior, to determine if there is enough soot present that could potentially harm the overall functionality of the sensor. Generally speaking, diesel engines produce an abnormal amount of soot anyway. That being said, aftermarket tuner upgrades can affect the fuel mixture and create higher-than-normal amounts of soot, which can consequently lead to premature NOx sensor failure, given the richer fuel mixtures involved with some aftermarket tuners. Make sure to clean the sensor if you suspect this is the case and return the fuel mixture to normal OEM specifications by removing or disabling the tuner.

Basic Step #4

Finally, if you have exhausted your resources and still cannot identify the issue, it would be a good idea to locate your ECM (Engine Control Module) to check for water intrusion. Sometimes, inside the vehicle, it can be prone to creating moisture inside over time (e.g., leaking heater core, leaking window seals, melting residual snow, etc.). If significant damage is found, it will need to be replaced. To do this, in most cases, the new ECM will need to be reprogrammed for the vehicle to ensure a seamless adaptation. Unfortunately, generally speaking, dealerships will be the only ones equipped with the appropriate programming tools.

This article is strictly for informational purposes only, and technical data and service bulletins for your specific vehicle should always take precedence.

How severe is this DTC?

Average severity for this, as emission-related faults can truly affect the environment around it. That said, sometimes with emission faults, there will be no symptoms present but can still have repercussions if left unaddressed.

What are some of the symptoms of the code?

Symptoms of a P2206 diagnostic code may include:

• Failed emissions test
• Intermittent CEL (Check Engine Light)

What are some common causes of the code?

Causes

of this P2206 cruise control code may include:

• Faulty NOx sensor
• Faulty NOx sensor heater
• Internal opening in the ECM (Engine Control Module) or the NOx sensor itself
• Water intrusion
• Broken connector tabs (intermittent connection)
• Melted harness
• Dirty sensor element
• High resistance present in the heater control circuit

What are the diagnostic and troubleshooting steps for P2206?

The first step in the troubleshooting process for any malfunction is to check the Technical Service Bulletins (TSBs) for known issues with the specific vehicle.

Advanced diagnostic steps become very vehicle-specific and may require the appropriate advanced equipment and knowledge to operate accurately. We include the basic steps below, but refer to a repair guide specific to the year/make/model/drivetrain for steps tailored to your vehicle.

Basic Step #1

Most NOx sensors used in automotive and diesel truck applications will be quite accessible. Given this fact, keep in mind that they can be extremely stubborn to remove with all the expansion and contraction that occurs with temperature fluctuations in the exhaust system. So, make sure you need to remove the sensor before doing so. Most sensor tests should be able to be performed from the connector. Refer to your service manual for pinpoint tests of the NOx sensor to obtain the desired values.

NOTE: You may need to use some heat when replacing the NOx sensor to avoid stripping the threads of the exhaust plug. Penetrating oil is always a good idea whenever you think you might remove the sensor in the near future.

Basic Step #2

Follow the harness involved with the NOx sensor to assess its condition. Most of the time, harnesses will be run near the extreme heats mentioned earlier. So, keep a close eye out for melted harnesses or connectors. Be sure to repair any chafing or damaged harnesses to prevent future malfunctions.

Basic Step #3

Visually inspect the exhaust system, especially the interior, to determine if there is enough soot present that could potentially harm the overall functionality of the sensor. Generally speaking, diesel engines produce an abnormal amount of soot anyway. That being said, aftermarket tuner upgrades can affect the fuel mixture and create above-normal amounts of soot, which can consequently lead to premature NOx sensor failure, given the richer fuel mixtures involved with some aftermarket tuners. Make sure to clean the sensor if you suspect this is the case and return the fuel mixture to normal OEM specifications by removing or disabling the tuner.

Basic Step #4

Finally, if you have exhausted your resources and still cannot identify the issue, it would be a good idea to locate your ECM (Engine Control Module) to check for water intrusion. Sometimes, inside the vehicle, it can be prone to creating moisture inside over time (e.g., heater core leak, window seal leak, melting residual snow, etc.). If significant damage is found, it will need to be replaced. To do this, in most cases, the new ECM will need to be reprogrammed for the vehicle to ensure a seamless adaptation. Unfortunately, generally speaking, dealerships will be the only ones equipped with the appropriate programming tools.

This article is strictly for informational purposes only, and the technical data and service bulletins for your specific vehicle should always take precedence.

How severe is this DTC?

Average severity for this, as emission-related faults can truly affect the surrounding environment. That said, sometimes with emission faults, there may be no symptoms present but can still have repercussions if left unaddressed.

What are some of the symptoms of the code?

Symptoms of a P2207 diagnostic code may include:

• Failed emissions test
• Intermittent CEL (Check Engine Light)

What are some common causes of the code?

Causes of the P2207 cruise control code may include:

• Faulty NOx sensor
• Faulty NOx sensor heater
• Internal opening in the ECM (Engine Control Module) or the NOx sensor itself
• Water intrusion
• Broken connector tabs (intermittent connection)
• Melted harness
• Dirty sensor element
• High resistance present in the heater control circuit

What are the diagnostic and troubleshooting steps for P2207?

The first step in the troubleshooting process for any malfunction is to check Technical Service Bulletins (TSBs) for known issues with the specific vehicle.

Advanced diagnostic steps become very vehicle-specific and may require the appropriate advanced equipment and knowledge to operate accurately. We include the basic steps below but refer to a repair guide specific to the year/make/model/drivetrain for steps tailored to your vehicle.

Basic Step #1

Most NOx sensors used in automotive and diesel truck applications will be fairly accessible. Given this fact, keep in mind that they can be extremely stubborn to remove due to all the expansion and contraction that occurs with temperature fluctuations in the exhaust system. Therefore, ensure you need to remove the sensor before doing so. Most sensor tests should be able to be performed from the connector. Refer to your service manual for pinpoint tests of the NOx sensor to obtain the desired values.

NOTE: You may need to use some heat when replacing the NOx sensor to avoid stripping the threads of the exhaust plug. Penetrating oil is always a good idea whenever you think you might remove the sensor in the near future.

Basic Step #2

Follow the harness involved with the NOx sensor to assess its condition. Most of the time, harnesses will be routed near the extreme heats mentioned earlier. So keep a close eye out for melted harnesses or connectors. Be sure to repair any chafing or damaged harnesses to prevent future malfunctions.

Basic Step #3

Visually inspect the exhaust system, especially the interior, to determine if there is enough soot present that could potentially harm the overall functionality of the sensor. Generally speaking, diesel engines produce an abnormal amount of soot anyway. That being said, aftermarket tuner upgrades can affect the fuel mixture and create above-normal amounts of soot, which can consequently lead to premature NOx sensor failure, given the richer fuel mixtures involved with some aftermarket tuners. Be sure to clean the sensor if you suspect this is the case and return the fuel mixture to normal OEM specifications by removing or disabling the tuner.

Basic Step #4

Finally, if you have exhausted your resources and still cannot identify the issue, it would be a good idea to locate your ECM (Engine Control Module) to check for water intrusion. Sometimes, inside the vehicle, it can be prone to creating moisture buildup over time (e.g., leaking heater core, leaking window seals, melting residual snow, etc.). If significant damage is found, it will need to be replaced. To do this, in most cases, the new ECM will need to be reprogrammed for the vehicle to ensure a seamless adaptation. Unfortunately, generally speaking, dealerships will be the only ones equipped with the appropriate programming tools.

This article is strictly for informational purposes only, and technical data and service bulletins for your specific vehicle should always take precedence.