P0474
Exhaust Pressure Sensor A Circuit IntermittentP0474 is a generic OBD-II powertrain diagnostic trouble code: Exhaust Pressure Sensor A Circuit Intermittent. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P0474 means
P0474 is set when the ECM detects that the Exhaust Pressure Sensor A circuit is producing an intermittent signal — one that drops out, spikes, or behaves inconsistently in a pattern that does not match the expected gradual change correlated with engine load and exhaust flow. Unlike P0472 (persistently low) or P0473 (persistently high), P0474 implies the fault is transient and may be absent during diagnosis.
Intermittent faults of this type are almost always electrical in origin: a hairline crack in the sensor body, a loose or partially corroded connector pin, a chafed wire that intermittently contacts a ground, or a pressure hose that partially disconnects under vibration. Heat cycling and engine vibration are the most common triggers for intermittent exhaust sensor faults on high-mileage vehicles.
Because the ECM cannot consistently act on an unreliable sensor signal, regeneration scheduling and EGR modulation based on exhaust back-pressure become erratic. This can lead to irregular soot loading behaviour and, over time, unexpected DPF blockage even when no persistent fault is present. Diagnosis requires replicating the fault condition — typically through a wiggle test on the wiring harness and connector while monitoring the live sensor PID.
Common causes
Most-frequently reported root causes when P0474 is logged.
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1
Intermittently loose or corroded sensor connector (most common cause of code P0474)
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2
Chafed signal wire making intermittent contact with chassis ground or adjacent wiring
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3
Cracked or partially detached pressure sensing hose that seals under static conditions but leaks under vibration
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4
Failing sensor with internal intermittent open circuit
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5
Poor crimps or damaged pin sockets at the ECM harness connector
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6
Sensor exposed to excessive heat causing intermittent thermal expansion failures
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7
Electromagnetic interference from nearby ignition or injection wiring on unshielded sensor cables
Symptoms drivers notice
How to diagnose P0474
A typical diagnostic flow when this code is present.
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1
Retrieve fault codes and note whether P0474 is stored as pending, confirmed, or history — a history code with no current fault indicates an intermittent condition
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2
Connect a scan tool and monitor the exhaust pressure sensor PID live; perform a wiggle test on the harness and connector while watching for signal spikes or dropouts
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3
Inspect the connector for bent, pushed-back, or corroded pins; apply contact cleaner and re-seat firmly
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4
Trace the sensor wiring for chafe points near hot exhaust components, sharp body edges, or cable ties that have worn through insulation
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5
Inspect pressure hoses for cracks that may open under vibration — flex the hose by hand while monitoring the PID
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6
If no fault is found statically, road-test over rough surfaces while logging the sensor channel to provoke the intermittent condition
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7
Replace the sensor as a final step if harness and hose integrity are confirmed good and the fault persists
Vehicles where we've handled P0474
Platforms in our catalogue with confirmed P0474 coverage.
Related powertrain codes
- P0400 — Exhaust Gas Recirculation Flow Malfunction
- P0401 — Exhaust Gas Recirculation Flow Insufficient Detected
- P0402 — Exhaust Gas Recirculation Flow Excessive Detected
- P0403 — Exhaust Gas Recirculation Circuit Malfunction
- P0404 — Exhaust Gas Recirculation Circuit Range/Performance
- P0405 — Exhaust Gas Recirculation Sensor A Circuit Low
Frequently asked questions
Why does P0474 clear itself only to come back later?
Intermittent faults self-clear when the physical fault condition (e.g. a loose connector) temporarily stops occurring. The ECM re-sets the code once the glitch meets the frequency or duration threshold in its diagnostic monitor, which is why the code appears, clears, and returns.
How do I reproduce an intermittent P0474 fault during diagnosis?
Use a scan tool to monitor the exhaust pressure PID live, then physically wiggle the sensor harness, flex the pressure hoses, and tap the sensor body. Any spike or dropout in the live reading that correlates with your manipulation identifies the fault location.
Can P0474 cause a failed emissions test?
Yes. An illuminated MIL from P0474 is an automatic emissions test failure in most jurisdictions. Even if symptoms are mild, the code must be diagnosed and repaired before the MIL can be cleared for a passing result.
Is it worth replacing the sensor without finding the root cause?
Replacing the sensor without confirming the sensor itself is faulty often wastes money. P0474 is most frequently caused by connector and wiring issues. Thoroughly inspect the harness first; replace the sensor only after the wiring has been ruled out.
Disabling P0474 in software
RaceTune can permanently disable P0474 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
ECUs with a P0474 disable in our catalogue
Confirmed coverage from our recipe database — we support many more families. Upload your file and our identifier will match it automatically.
- Bosch EDC17C74 verified 1 software version
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
Got P0474 in your scan?
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