What Happens If the Exhaust Pressure Sensor Is Faulty?

A faulty exhaust pressure sensor can trigger a check-engine light, cause poor performance or limp mode, disrupt DPF regeneration, worsen fuel economy, and increase emissions; in severe cases it can lead to turbo and emissions-system damage if ignored. This sensor—often called an exhaust back-pressure (EBP) sensor or a diesel particulate filter (DPF) differential pressure sensor—helps the engine computer gauge exhaust flow and restriction. When it fails or its tubing is clogged, the engine receives bad data and makes poor control decisions.

Why the Exhaust Pressure Sensor Matters

Modern engines, especially diesels, rely on precise exhaust pressure readings to manage turbocharger operation, EGR (exhaust gas recirculation), and DPF regeneration. The sensor may measure absolute pressure upstream of the turbo, or differential pressure across the DPF to estimate soot loading. Incorrect readings upset this balance, triggering protective strategies and drivability issues.

Common Symptoms You’ll Notice

These are the typical signs drivers experience when the exhaust pressure sensor or its plumbing is faulty. The list helps you connect real-world symptoms to a potential sensor issue.

• Check Engine Light (MIL), sometimes with “Service Emissions System” messages
• Reduced power or limp mode, especially under load
• Poor fuel economy and sluggish acceleration
• Frequent, failed, or interrupted DPF regenerations (diesels)
• Rough idle, surging, or hard starts
• Excess smoke (black during acceleration or white during failed regens)
• Overheating exhaust components or elevated exhaust gas temperatures
• Turbo control problems (over/under-boost) and erratic EGR flow

While any single symptom can have multiple causes, a pattern of emissions warnings with driveability issues often points to an exhaust pressure sensing or plumbing fault.

What’s Actually Going Wrong

When an exhaust pressure sensor fails electrically or is fed by soot-clogged or cracked tubes, it can report pressure that is too high, too low, or stuck. The engine computer may then miscalculate DPF soot load, command unnecessary regens, delay needed regens, or mismanage turbo and EGR flow. Prolonged operation can rapidly load the DPF, stress the turbo, and raise emissions.

Typical Trouble Codes You Might See

These OBD-II codes frequently accompany exhaust pressure sensor or line faults. This helps narrow diagnosis before parts are replaced.

• P0470–P0473: Exhaust Pressure Sensor Circuit/Range/Performance
• P0474: Exhaust Pressure Sensor Intermittent
• P2452–P2454: DPF Differential Pressure Sensor Circuit/Range
• P2463: DPF Soot Accumulation
• P2002: DPF Efficiency Below Threshold
• P0299/P0234: Turbo underboost/overboost (secondary effect)

Freeze-frame data and live readings are crucial—codes alone can’t distinguish a bad sensor from blocked tubing or wiring faults.

Risks of Continuing to Drive

Before deciding to keep driving, consider the potential consequences below. These points outline both safety and cost risks.

• Engine derate or no-start after multiple failed DPF regens (diesels)
• Accelerated DPF clogging and possible need for off-vehicle cleaning or replacement
• Turbocharger stress from incorrect vane/boost control
• Higher emissions and possible inspection failure
• Potential catalyst/DPF overheating during forced or failed regens

Short trips to a workshop are usually fine if the vehicle is stable, but extended driving risks expensive damage—especially on diesel models with a DPF.

How Technicians Diagnose the Fault

Effective diagnosis separates sensor failure from issues like soot-clogged pressure lines, exhaust leaks, or wiring problems. These steps outline a typical, efficient workflow.

1. Scan for codes and review freeze-frame data; note operating conditions when the fault set.
2. Inspect the rubber/metal pressure lines to the sensor for soot blockage, melting, kinks, or cracks; clean or replace as needed.
3. Check electrical connectors and harness for corrosion, oil intrusion, chafing, or poor grounds.
4. Verify Key-On Engine-Off reading: exhaust pressure should be near barometric pressure; differential pressure should be near zero.
5. Compare exhaust pressure data to MAP/boost and ambient readings for plausibility.
6. Apply gentle pressure/vacuum with a hand pump to the sensor port and confirm the signal changes smoothly.
7. Smoke-test for pre-turbo exhaust leaks that can skew readings.
8. Check for ECM calibration updates related to emissions/pressure sensing.

A methodical approach prevents unnecessary sensor replacement when the real culprit is a plugged tube or wiring fault.

Fixes, Costs, and After-Repair Steps

Once the root cause is known, these are the common remedies and what to expect for cost and follow-up. This helps set expectations before authorizing repairs.

• Replace the exhaust pressure or DPF differential pressure sensor: parts typically $40–$250, labor 0.5–1.5 hours
• Clean/replace clogged pressure hoses and metal stubs; ensure correct routing and heat shielding
• Repair wiring/connectors; apply dielectric grease where appropriate
• Address exhaust leaks upstream of the turbo/DPF
• Reset learned soot values if specified by the manufacturer
• Perform a service regeneration or DPF cleaning if soot load is high
• Update ECM software if a TSB/recall applies

After repairs, a road test while monitoring live data should confirm stable readings and proper regen behavior, with all monitors set and no returning codes.

Prevention and Best Practices

You can reduce the likelihood of exhaust pressure sensor issues with a few habits and maintenance steps. These guidelines aim to prolong emissions-system health.

• Use high-quality fuel and keep up with oil changes to limit soot
• Allow complete, uninterrupted DPF regens (especially for urban driving patterns)
• Inspect pressure lines during routine services; replace softened or brittle hoses
• Avoid aftermarket tunes that disable or distort emissions controls
• Address small exhaust leaks promptly—pre-turbo leaks skew sensor data

Regular attention to these basics keeps the emissions system clean and reduces sensor and DPF stress over time.

Safety Note

Exhaust components get extremely hot. Allow ample cooldown before touching sensors or lines, and use proper PPE when working around the exhaust and turbo.

Bottom Line

A faulty exhaust pressure sensor—or its clogged, heat-battered plumbing—can set off a cascade of drivability and emissions problems, from limp mode to DPF damage. Quick diagnosis, usually starting with hose inspection and live-data checks, prevents bigger bills and keeps your engine and aftertreatment system healthy.

Summary

If the exhaust pressure sensor is faulty, expect warning lights, reduced power, poor fuel economy, disrupted DPF regens, and potential turbo/emissions damage if ignored. Diagnosis focuses on codes, line blockages, wiring, and plausibility checks; fixes range from hose cleaning to sensor replacement and, if needed, DPF service. Prompt attention limits cost and protects engine and emissions components.

What are the symptoms of a bad exhaust gas sensor?

Symptoms of a Faulty EGTS

• Check Engine Light.
• Reduced Fuel Efficiency.
• Unnecessary DPF Regeneration.
• Failed Emissions Test.
• Component Failure.

How do you know if your pressure sensor is bad?

What are the 6 signs of a faulty fuel tank pressure sensor?

• Check engine light comes on.
• Fuel efficiency reduces.
• Your vehicle’s emissions go up.
• You experience a hard start.
• You notice a weird odour or smell.

What does an exhaust pressure sensor do?

An exhaust pressure sensor monitors exhaust gas back pressure to maintain optimal diesel particulate filter (DPF) and exhaust gas recirculation (EGR) system performance. It measures pressure differences to detect soot buildup in the DPF, allowing the engine control unit (ECU) to trigger the DPF regeneration process to clear the filter and prevent clogging. In addition, it helps the ECU regulate the EGR system and control turbocharger operation to improve engine performance, fuel efficiency, and emissions. 
How it Works

• Measuring Pressure: The sensor is typically a differential pressure sensor that measures the pressure of exhaust gases before and after a component, such as a DPF. 
• Sending Data to the ECU: This information is sent to the engine’s control unit (ECU). 
• Triggering Actions: The ECU then uses this data to: 
  • Regenerate the DPF: If the pressure difference indicates a clogged DPF, the ECU can initiate a DPF regeneration cycle to burn off trapped soot and restore proper flow. 
  • Control EGR and Turbo: It helps regulate the EGR valve for proper air-fuel mixture and adjust the turbocharger for optimal performance. 

Symptoms of a Faulty Sensor

• Loss of Engine Power: Without proper exhaust flow, the engine can struggle, leading to reduced power. 
• Poor Fuel Economy: The engine working harder due to restricted exhaust or incorrect engine adjustments can cause lower fuel efficiency. 
• Warning Lights: A fault in the exhaust pressure sensor will often trigger a check engine light on the dashboard. 
• Limp Mode: The vehicle may enter limp mode, limiting its speed and power until the issue is addressed. 

What happens when an exhaust pressure sensor goes bad?

Symptoms of a failing exhaust pressure sensor include the Check Engine light or other warning lights illuminating, rough idling, reduced engine power, poor fuel economy, engine hesitation, and potentially a failed emissions test. A diagnostic scanner will typically reveal a specific error code, such as P0471, indicating a fault with the sensor’s circuit or readings. 
Common Symptoms

• Illuminated Dashboard Lights: The Check Engine light is the most obvious indicator of a sensor issue, as the vehicle’s computer (ECU) is no longer receiving accurate pressure data. 
• Engine Performance Issues: A faulty sensor can cause a rough idle, poor acceleration, and an overall loss of power because the engine’s control unit doesn’t have the correct pressure information to optimize its function. 
• Increased Fuel Consumption: Inaccurate readings can lead the ECU to believe the engine isn’t expelling exhaust gas efficiently, causing it to try and compensate by using more fuel. 
• Hesitation or Stalling: Incorrect pressure data can disrupt the air-fuel mixture, leading to engine hesitation during acceleration or even complete stalling. 
• Failed Emissions Tests: The sensor plays a role in the vehicle’s emissions control system, so a malfunctioning one can prevent the vehicle from passing an emissions test. 
• Soot Buildup: In diesel engines, an exhaust pressure sensor issue can contribute to excessive soot buildup in the diesel particulate filter (DPF). 

Troubleshooting and Next Steps

1. Read the Diagnostic Trouble Codes (DTCs): Use a diagnostic scanner to retrieve error codes, such as P0470 or P0471, which pinpoint a problem with the exhaust pressure sensor. 
2. Inspect Wiring and Connectors: Check the sensor’s wiring and connectors for any signs of damage, corrosion, or loose connections, which can interfere with the signal. 
3. Professional Diagnosis: If the symptoms persist or you’re unsure of the cause, it’s best to have a qualified mechanic perform a thorough diagnosis and replace the faulty sensor.