P0473 is a diagnostic trouble code that can show up on many diesel and turbocharged gas engines, and it usually points to an electrical problem with the exhaust back pressure sensor circuit. When this code appears, your ECU is seeing a voltage signal that’s higher than it expects. That can affect how the engine controls boost, EGR flow, and overall performance. In this guide, you’ll learn what P0473 means, common symptoms, likely causes, how to diagnose it at home, and what repairs typically cost at a shop.
What Does P0473 Mean?
P0473 stands for “Exhaust Pressure Sensor ‘A’ Circuit High.” Your engine control unit (ECU) monitors exhaust back pressure through a sensor, usually mounted on or near the exhaust manifold with a small tube running from the exhaust to the sensor. The sensor converts pressure into a voltage signal.
When the ECU sees a voltage that’s higher than the programmed range, it sets P0473. This can be caused by a wiring issue, a failed sensor, or a problem in the reference/ground circuit. On many diesel trucks, this code is closely tied to turbo and EGR control, so it’s worth fixing promptly.
Quick Reference
- Code: P0473
- Definition: Exhaust Pressure Sensor “A” Circuit High
- System: Exhaust / Engine Management
- Severity: Moderate – can affect drivability and emissions
- Typical Fixes: Repair wiring, clean/replace exhaust pressure sensor, clear clogged sensor tube
Real-World Example / Field Notes
On many Ford Powerstroke and Ram Cummins trucks, I see P0473 pop up when the exhaust back pressure sensor tube gets packed with carbon. The owner usually complains of low power, higher fuel consumption, and sometimes erratic turbo behavior. A quick check with a scan tool shows the exhaust pressure reading stuck high even with the key on, engine off. Cleaning or replacing the sensor and tube, then repairing any corroded wiring at the connector, usually clears the code and restores normal performance.
Symptoms of P0473
- Check engine light on: The MIL/SES light will almost always be illuminated.
- Reduced power: You may feel sluggish acceleration or a “lazy” turbo response.
- Poor fuel economy: Incorrect exhaust pressure readings can cause richer fueling.
- Rough running: Idle may feel unstable, especially when the engine is warm.
- Regeneration issues (diesel): DPF regens may be more frequent or fail to complete.
- Harsh or odd shifting (automatics): Some vehicles adjust shift strategy based on load data.
- Other exhaust/turbo codes: You might see related EGR or boost control codes stored with P0473.
Common Causes of P0473
Most Common Causes
- Failed exhaust pressure sensor: Internal sensor failure causing a constant high-voltage signal.
- Clogged sensor tube: Carbon buildup in the tube between the exhaust and sensor, skewing readings.
- Short to voltage in signal wire: Damaged insulation or rubbing harness feeding extra voltage to the sensor circuit.
- Bad sensor ground: Corroded or loose ground causing the ECU to see an artificially high signal.
- Connector corrosion: Moisture and road salt inside the plug raising resistance and altering the signal.
Less Common Causes
- Faulty 5V reference circuit: Shared reference line with other sensors going above spec.
- ECU internal fault: Rare, but a damaged driver circuit can misread the sensor voltage.
- Aftermarket tuning issues: Poorly written tunes or deleted systems confusing the exhaust pressure strategy.
- Exhaust modifications: Extreme changes (oversized turbo, custom manifolds) without proper calibration.
- Rodent or impact damage: Chewed or pinched wiring harness near the turbo or exhaust.
Diagnosis: Step-by-Step Guide
To diagnose P0473 properly, you’ll want a basic scan tool (preferably one that can read live data and Mode $06), a digital multimeter, and simple hand tools. A wiring diagram for your specific vehicle is very helpful, and safety gear (gloves, eye protection) is a must when working around hot exhaust components.
- Confirm the code: Use a scan tool to verify P0473 is active. Check for other related codes (EGR, turbo, boost, DPF). Record freeze-frame data so you know under what conditions it set.
- Visual inspection: With the engine cool, locate the exhaust pressure sensor and its tube. Look for melted wiring, rubbed-through insulation, loose connectors, and heavy corrosion at the plug.
- Check sensor tube: Remove the tube (if accessible) and inspect for carbon blockage. If plugged, clean it with a suitable solvent or replace it. Make sure the ports on the manifold and sensor are open.
- Key-on, engine-off data check: With the key on and engine off, monitor exhaust pressure on your scan tool. It should read close to atmospheric pressure (often near 0 psi or a low kPa value). If it shows a very high reading, suspect the sensor or wiring.
- Verify reference voltage and ground: Unplug the sensor. Using a multimeter, check for a stable 5V reference and a good ground at the connector. A missing or high reference, or a floating ground, points to wiring or ECU issues.
- Test signal wire for short to voltage: With the sensor unplugged, backprobe the signal wire. It should not show full battery voltage. If it does, you likely have a short to power somewhere in the harness.
- Sensor resistance/voltage test: Follow your service manual to test the sensor. Some sensors can be bench-tested by applying pressure and watching voltage change; others are best verified by substitution with a known-good unit.
- Wiggle test: With the engine running and live data displayed, gently move the harness and connector. If the exhaust pressure reading jumps around or spikes high, you’ve found an intermittent wiring or connector issue.
- Clear codes and road test: After repairs, clear the codes and perform a road test under similar conditions to the freeze-frame data. Re-scan to confirm P0473 does not return.
Pro tip: On many diesel trucks, if the exhaust pressure sensor has failed or the tube is heavily clogged, it’s smart to inspect and clean the EGR passages and check DPF load, since excessive soot in one area often means buildup elsewhere.
Possible Fixes & Repair Costs
Repairs for P0473 range from simple cleaning to component replacement. Cleaning a clogged exhaust pressure sensor tube and ports is often the cheapest fix and can be done in under an hour. Replacing the exhaust pressure sensor itself is common; parts typically run $50–$200, with labor adding $80–$200 depending on access. Wiring repairs, such as fixing a shorted harness or corroded connector, can range from $100–$400. In rare cases where the ECU is at fault, you may be looking at $500–$1,200 or more including programming. Costs vary by vehicle, labor rates, and how difficult the sensor is to reach.
Can I Still Drive With P0473?
You can usually drive with P0473 for a short period, but it’s not ideal. The ECU may switch to a backup strategy, which can reduce power, hurt fuel economy, and increase soot production. On some diesel trucks, you might eventually hit a limp mode if the system can’t control exhaust pressure correctly. If the vehicle feels unsafe, has severe power loss, or starts showing additional codes, you should avoid driving and have it inspected as soon as possible.
What Happens If You Ignore P0473?
Ignoring P0473 can lead to long-term issues like excessive soot buildup, more frequent or failed DPF regenerations, and premature wear on the turbocharger and EGR components. Over time, that can turn a relatively simple electrical or sensor problem into expensive hardware failures and extended downtime.
Related Codes
- P0474 – Exhaust Pressure Sensor Intermittent
- P0472 – Exhaust Pressure Sensor Low
- P0471 – Exhaust Pressure Sensor Range/Performance
- P0470 – Exhaust Pressure Sensor
- P0469 – EVAP Purge Flow Sensor Circuit Intermittent
- P0468 – EVAP Purge Flow Sensor Circuit High
- P0467 – EVAP Purge Flow Sensor Circuit Low
- P0466 – EVAP Purge Flow Sensor Circuit Range/Performance
- P0465 – EVAP Purge Flow Sensor Circuit
- P0464 – Fuel Level Sensor “A” Circuit Intermittent
Key Takeaways
- P0473 means the ECU sees a high-voltage signal from the exhaust pressure sensor “A” circuit.
- The most common culprits are a bad sensor, clogged sensor tube, or wiring/connector problems.
- Symptoms include a check engine light, reduced power, poor fuel economy, and possible DPF/EGR issues.
- Diagnosis involves checking live data, inspecting and cleaning the sensor tube, and testing wiring and voltage.
- Repairs usually fall in the $100–$400 range, but can be higher if major components or the ECU are involved.
Vehicles Commonly Affected by P0473
P0473 is especially common on modern diesel pickups and vans that rely heavily on exhaust pressure feedback. You’ll often see it on Ford Powerstroke trucks (6.0L, 6.4L, 6.7L), Ram trucks with Cummins engines, and GM Duramax-equipped Chevy and GMC models. Some turbocharged gas engines from Ford, Volkswagen, Audi, and Mercedes-Benz can also set this code. Fleet vehicles and work trucks that see a lot of idling, towing, or stop-and-go driving tend to experience more soot buildup, which increases the odds of exhaust pressure sensor problems.
FAQ
Can I clear P0473 and keep driving without fixing it?
You can clear the code, but it will usually return if the underlying issue is still there. Driving without fixing it can lead to poor performance, higher fuel use, and additional exhaust or turbo problems over time.
Is P0473 always caused by a bad exhaust pressure sensor?
No. While the sensor itself fails often, P0473 can also be caused by a clogged sensor tube, damaged wiring, poor ground, or a faulty 5V reference. Testing before replacing parts saves money.
How do I know if the exhaust pressure sensor tube is clogged?
If the scan tool shows an abnormally high exhaust pressure reading with the key on and engine off, or the reading doesn’t change with engine speed, the tube may be blocked. Removing it and checking for heavy carbon buildup is the best confirmation.
Can a tune or delete cause P0473?
Yes, poorly written aftermarket tunes or emissions deletes can confuse the ECU’s exhaust pressure strategy and trigger P0473. If the code started right after tuning, have the calibration checked or reverted to stock.
How urgent is it to fix P0473 on a diesel truck?
It’s not an immediate “park it now” emergency in most cases, but you shouldn’t ignore it. Fixing P0473 promptly helps protect your turbo, DPF, and EGR system, and keeps the truck running efficiently and reliably.