What is the difference between EGR sensor A and sensor B?

Sensor A is the primary EGR position feedback. Sensor B is the second one, found only on engines with two EGR valves or two EGR circuits, such as diesels that use both high-pressure and low-pressure EGR (many VW Group EA288 engines work this way). Which of the two the manufacturer calls B is defined in its service data, so read the fault with manufacturer-level software before replacing a valve. Engines with a single EGR valve have no sensor B.

Can I drive with P0407?

Short-term yes. The ECU may stop using the affected EGR circuit, which can cause uneven idle and reduced power, and some diesels enter limp mode. Plan the repair within a couple of weeks to avoid carbon buildup or DPF problems.

Does my 4-cylinder car have an EGR sensor B?

It depends on the EGR layout, not the number of cylinders. A four-cylinder diesel with both a high-pressure and a low-pressure EGR circuit, such as many VW Group EA288 engines, has a valve and position feedback for each, so it can set P0407. An engine with a single EGR valve has no sensor B, so if P0407 appears there, recheck the code and look up the manufacturer's own definition.

Is repairing P0407 worth it on a high-mileage diesel?

Yes, in most cases. EGR sensor or valve replacement is far cheaper than dealing with the clogged DPF or other after-treatment faults that can follow from an EGR system that is not working. On an engine with two EGR valves, have both inspected while the work is being done, since they share the same age and soot exposure.

P0407: Exhaust Gas Recirculation Sensor "B" Circuit Low

Quick Answer

Safe to drive (short-term)

P0407 means EGR position sensor 'B' is sending a voltage below its normal operating range. Sensor B only exists on engines with a second EGR valve or a second EGR circuit, for example diesels that combine high-pressure and low-pressure EGR, and the manufacturer decides which of the two is called B. The fault is usually wiring or a failed sensor pulling the signal to ground.

Severity: Moderate · Emissions
Estimated repair cost: From €70 to €730+, varies by vehicle

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What does P0407 mean?

P0407 is a emissions-related diagnostic trouble code classified as moderate severity. When your vehicle's ECU detects this condition, it stores P0407 and illuminates the check engine light.

Where it is on the car

Engine
Exhaust manifold
EGR cooler (diesels and many newer petrols)
EGR valve and position sensor
Intake manifold

Sensor B exists only on engines with a second EGR valve or a second EGR circuit, for example some diesels with high and low pressure EGR.

What are the symptoms of P0407?

If your vehicle has triggered P0407, you may notice one or more of these symptoms:

Check engine light illuminated
Rough or uneven idle
Reduced power, possible limp mode on diesels
Hesitation during acceleration
Failed emissions or periodic technical inspection

What causes P0407?

Here are the most common causes of P0407:

EGR position sensor B shorted to ground internally
: high
Damaged signal wire from sensor B grounding against engine components
: high
Corroded sensor B connector pulling signal low
: medium
Open 5V reference to sensor B (less common, often affects both sensors)
: medium
Failed ECU driver for sensor B circuit (rare)
: low

Is it safe to drive with P0407?

Generally yes, for short-term driving. Driveable. P0407 affects the second EGR position sensor (sensor B), present only on engines with two EGR valves or two EGR circuits. The ECU loses confidence in that feedback and may stop using the affected EGR circuit, and some diesels reduce power. A stored EGR fault is likely to be flagged at an emissions check.

How do you diagnose P0407?

Follow these steps to pinpoint the root cause of P0407:

Identify which physical valve or sensor is 'B' in the manufacturer's service data. On engines with high- and low-pressure EGR it belongs to one of the two circuits, and manufacturer-level software names it directly
Back-probe the sensor B signal wire. A healthy sensor at rest reads 0.5-1.0V. Below 0.2V indicates short to ground
Verify 5V reference and ground at sensor B connector. If 5V reference is missing, check whether sensor A is also affected
Inspect the harness branch for sensor B for chafing against hot exhaust parts or heat shields
Replace sensor B (or the integrated valve assembly) if wiring tests good and signal reads steadily low

How much does P0407 cost to fix?

Repair costs for P0407 vary depending on the root cause and your vehicle. Here are typical estimates:

Repair	Parts Cost	Labor Cost	Total Estimate	DIY Difficulty
Clean and repair sensor B connector	€10–€60	€60–€180	€70–€240	Moderate
Replace EGR valve B (sensor integrated)	€150–€450	€100–€280	€250–€730	Moderate
Repair EGR wiring harness (sensor B branch)	€20–€120	€120–€350	€140–€470	Professional

Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.

Full repair guides

EGR Valve Replacement Cost

P0407 on specific vehicles

P0407 behaves differently depending on your vehicle. Select your car below for model-specific causes and known issues:

P0407 on Volkswagen

Volkswagen Golf

See Volkswagen-specific causes & cost

These codes are often seen alongside P0407 or indicate related issues:

Common questions about P0407

What is the difference between EGR sensor A and sensor B?: Sensor A is the primary EGR position feedback. Sensor B is the second one, found only on engines with two EGR valves or two EGR circuits, such as diesels that use both high-pressure and low-pressure EGR (many VW Group EA288 engines work this way). Which of the two the manufacturer calls B is defined in its service data, so read the fault with manufacturer-level software before replacing a valve. Engines with a single EGR valve have no sensor B.
Can I drive with P0407?: Short-term yes. The ECU may stop using the affected EGR circuit, which can cause uneven idle and reduced power, and some diesels enter limp mode. Plan the repair within a couple of weeks to avoid carbon buildup or DPF problems.
Does my 4-cylinder car have an EGR sensor B?: It depends on the EGR layout, not the number of cylinders. A four-cylinder diesel with both a high-pressure and a low-pressure EGR circuit, such as many VW Group EA288 engines, has a valve and position feedback for each, so it can set P0407. An engine with a single EGR valve has no sensor B, so if P0407 appears there, recheck the code and look up the manufacturer's own definition.
Is repairing P0407 worth it on a high-mileage diesel?: Yes, in most cases. EGR sensor or valve replacement is far cheaper than dealing with the clogged DPF or other after-treatment faults that can follow from an EGR system that is not working. On an engine with two EGR valves, have both inspected while the work is being done, since they share the same age and soot exposure.

Read our detailed guides

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