P0474Generic code

P0474 Code: Exhaust Pressure Sensor Intermittent

The P0474 code indicates intermittent dropouts or jumps in the signal from the exhaust pressure sensor. The main effects are a loss of power and degraded turbo control.

Severity
Medium
Can I keep driving?
Yes, but with caution
Estimated cost
$50 to $400
Difficulty
Medium
System
Emissions Control
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

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What the P0474 code means

The exhaust back pressure (EBP) sensor measures the back pressure in the exhaust manifold. It is typical of turbo diesels with a variable geometry turbo and an exhaust pressure valve, such as the Ford Power Stroke and International engines.

The sensor gets a 5 V reference and a ground from the computer and sends back a signal between roughly 0.5 and 4.5 V. The P0474 code flags intermittent dropouts, and those almost always come from a bad contact or a damaged wire.

The computer uses this pressure to control the turbo, the EGR and the exhaust pressure valve (which helps warm up the engine when cold). If the signal fails, the turbo and the EGR lose their reference and a loss of power usually follows. The tube that carries pressure to the sensor clogs with soot very often. Look up the sensor guide to see how it is tested.

Intermittent faults are found by reproducing them. With the engine running and the scan tool in graph mode, move the wiring harness section by section, tap the connector gently and, if needed, warm the area with a hair dryer or wet the connector with a spray bottle. The point where the reading jumps is the point of the fault.

P0474 code symptoms

  • Check engine light on.
  • Loss of power and degraded turbo control.
  • Emissions monitor incomplete, so the vehicle cannot pass inspection.
  • Loss of power or uneven running.

Likely causes of the P0474 code

  1. Bad contact in the connector from loose or backed-out pins.
  2. Wire broken inside its insulation from vibration.
  3. Connector exposed to water on sensors mounted under the vehicle.
  4. Sensor with an intermittent fault, often temperature related.

How to diagnose the P0474 code step by step

  1. Read the sensor value on the scan tool and compare it with what you expect.
  2. Inspect the connector for corrosion, water or loose pins.
  3. Check the reference and ground with the key on (5 V, and less than 0.1 V of voltage drop on the ground).
  4. Measure the signal with the connector plugged in and see whether it changes with conditions.
  5. Do a wiggle test on the wiring.
  6. Check continuity to the computer.
  7. With the engine off, compare exhaust pressure and barometric pressure. They should match.
  8. Clean or replace the pressure tube from the manifold to the sensor, which often plugs with soot.

How to fix the P0474 code

  • Repair the connector or the wiring.
  • Replace the sensor if the tests confirm it is bad.
  • Correct the real condition if there is one (a leak or a blockage).
  • Clear the codes and complete a drive cycle so the monitor runs.

Technical reference data

  • 5 V reference, ground and signal.
  • Engine off: atmospheric pressure.
  • Approximate values only: check the manufacturer data for your engine.

Brand-specific notes

The sensor tube is the first thing to check on diesels, because soot plugs it more often than the sensor fails.

P0474 on Ford

Very common on the Ford Power Stroke 6.0 and 7.3, where the sensor tube plugs with soot.

P0474 on International

Very common on International engines, where the sensor tube plugs with soot.

Frequently asked questions about P0474

Can I drive with a P0474 code?
With caution. A P0474 code can come with a loss of power, so avoid heavy loads until it is checked.
Do I have to replace the sensor?
Only if the tests confirm it. The connector and the wiring fail just as often as the sensor.
Will I pass the inspection with this code?
No. The check engine light being on, or the monitor being incomplete, keeps the vehicle from passing.
How much does it cost to fix P0474?
Roughly $50 to $400, depending on whether it is a clogged tube, a connector, wiring or the sensor itself.
What does the P0474 code mean?
It is a generic OBD2 code for an intermittent signal from the exhaust pressure sensor. The reading drops out or jumps instead of staying steady.
What is the most common cause of P0474?
A bad contact in the connector or a wire broken inside its insulation. Wiggling the harness with the scan tool in graph mode usually shows where.

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