P0407: Exhaust Gas Recirculation Sensor "B" Circuit Low
Moderate SeveritySafe to drive (short-term)Emissions
P0407 means the EGR position sensor 'B' is sending a voltage below the normal operating range. Sensor B exists on engines with dual EGR valves (V6 and V8 diesels) or on petrol engines that use a primary and secondary feedback sensor. The fault is almost always wiring or a failed sensor shorted to ground.
Estimated repair costFrom €70 to €730+, varies by vehicle
What does P0407 mean?
P0407 means the EGR position sensor 'B' is sending a voltage below the normal operating range. Sensor B exists on engines with dual EGR valves (V6 and V8 diesels) or on petrol engines that use a primary and secondary feedback sensor. The fault is almost always wiring or a failed sensor shorted to ground.
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.
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 idle, sometimes uneven cylinder firing on V6/V8 diesels
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, ranked by how likely they are to be the culprit:
highEGR position sensor B shorted to ground internally
highDamaged signal wire from sensor B grounding against engine components
mediumCorroded sensor B connector pulling signal low
mediumOpen 5V reference to sensor B (less common, often affects both sensors)
lowFailed ECU driver for sensor B circuit (rare)
Is it safe to drive with P0407?
Generally yes, for short-term driving. Driveable. P0407 affects the second EGR position sensor (sensor B), present on engines with dual EGR valves or dual feedback sensors. The ECU loses confidence in EGR position feedback and may disable EGR or enter limp mode on diesels. Failed emissions test is guaranteed.
How do you diagnose P0407?
Follow these steps to pinpoint the root cause of P0407:
Identify which physical sensor is sensor B (workshop manual). On V6/V8 diesels, this is usually the bank opposite to sensor A
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 the EGR cooler or exhaust manifold heat shield
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.
P0407 on specific vehicles
P0407 behaves differently depending on your vehicle. Select your car below for model-specific causes, known issues, and adjusted cost estimates:
P0407 on BMW 3 Series
BMW 3 Series • 2014–2024
P0407 on a 3 Series typically appears on the 330d and 335d with B57 inline-6 diesel, which uses two EGR feedback sensors (high-pressure and low-pressure EGR). Sensor B is usually the low-pressure EGR position. The harness for the low-pressure sensor routes near the rear of the engine and is prone to chafing where it crosses the transmission tunnel. ISTA is required for adaptation reset.
What causes P0407 on a BMW 3 Series?
BMW 3 SeriesB57 low-pressure EGR sensor B short from harness chafing at transmission tunnel
BMW 3 SeriesDual high/low pressure EGR system, both feedback sensors must work
P0407 repair cost for BMW 3 Series
Estimated costs for BMW 3 Series ownersadjusted higher than average due to BMW-specific parts pricing
Repair
Parts Cost
Labor Cost
Total Estimate
DIY Difficulty
Clean and repair sensor B connector
€14–€84
€84–€252
€98–€336
Moderate
Replace EGR valve B (sensor integrated)
€210–€630
€140–€392
€350–€1022
Moderate
Repair EGR wiring harness (sensor B branch)
€28–€168
€168–€490
€196–€658
Professional
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
P0407 on Volkswagen Golf
Volkswagen Golf • 2012–2024
P0407 is uncommon on Golf TDIs because most 4-cylinder EA189/EA288 engines only have a single EGR position sensor. When it appears, it usually means the freeze frame labels the sole position sensor as 'B' in a market-specific calibration, or the vehicle has the rare high/low-pressure EGR variant fitted to some commercial Caddy and Crafter derivatives. VCDS confirms which sensor is at fault.
What causes P0407 on a Volkswagen Golf?
Volkswagen GolfRare high/low-pressure EGR variant on commercial Crafter/Caddy derivatives
Volkswagen GolfMarket-specific calibration labeling the single position sensor as 'B'
P0407 repair cost for Volkswagen Golf
Estimated costs for Volkswagen Golf ownersadjusted higher than average due to Volkswagen-specific parts pricing
Repair
Parts Cost
Labor Cost
Total Estimate
DIY Difficulty
Clean and repair sensor B connector
€12–€69
€69–€207
€81–€276
Moderate
Replace EGR valve B (sensor integrated)
€173–€518
€115–€322
€288–€839
Moderate
Repair EGR wiring harness (sensor B branch)
€23–€138
€138–€402
€161–€541
Professional
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
P0407 on Audi A4
Audi A4 • 2010–2024
P0407 is most common on the A4 3.0 TDI V6 (CCWA, CTBA, CAPA codes), which uses two EGR valves with two position sensors. Sensor B is the bank-2 EGR position. The harness for bank 2 routes behind the engine and is hard to access. Many shops replace both EGR valves together on high-mileage 3.0 TDI cars to avoid a repeat job. VCDS or ODIS adaptation reset for both banks is mandatory.
What causes P0407 on a Audi A4?
Audi A43.0 TDI V6 bank-2 EGR position sensor failure (sensor B)
Audi A4Both EGR valves usually replaced together on high-mileage cars
P0407 repair cost for Audi A4
Estimated costs for Audi A4 ownersadjusted higher than average due to Audi-specific parts pricing
Repair
Parts Cost
Labor Cost
Total Estimate
DIY Difficulty
Clean and repair sensor B connector
€13–€75
€75–€225
€88–€300
Moderate
Replace EGR valve B (sensor integrated)
€188–€563
€125–€350
€313–€913
Moderate
Repair EGR wiring harness (sensor B branch)
€25–€150
€150–€438
€175–€588
Professional
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
P0407 on Mercedes Sprinter
Mercedes Sprinter • 2014–2024
OM642 V6 diesel Sprinters (3.0 CDI) use dual EGR valves with dual sensors. P0407 indicates the bank-2 (left bank) position sensor is reading low. OM651 4-cylinder Sprinters do not typically have a sensor B, so P0407 on an OM651 usually points to a wiring labeling issue. XENTRY required for proper adaptation reset on V6 OM642 after sensor or valve service.
What causes P0407 on a Mercedes Sprinter?
Mercedes SprinterOM642 V6 bank-2 EGR sensor B short to ground
Mercedes SprinterOM651 4-cylinder: P0407 usually indicates wiring or naming issue, not sensor B
P0407 repair cost for Mercedes Sprinter
Estimated costs for Mercedes Sprinter ownersadjusted higher than average due to Mercedes-specific parts pricing
Repair
Parts Cost
Labor Cost
Total Estimate
DIY Difficulty
Clean and repair sensor B connector
€13–€78
€78–€234
€91–€312
Moderate
Replace EGR valve B (sensor integrated)
€195–€585
€130–€364
€325–€949
Moderate
Repair EGR wiring harness (sensor B branch)
€26–€156
€156–€455
€182–€611
Professional
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
Related diagnostic codes
These codes are often seen alongside P0407 or indicate related issues:
What is the difference between EGR sensor A and sensor B?
Sensor A is the primary EGR position feedback. Sensor B is the secondary, present on engines with two EGR valves (most V6/V8 diesels) or on engines that use a redundant feedback sensor. On most 4-cylinder engines there is no sensor B, so P0407 only appears on more complex setups (Audi 3.0 TDI V6, Mercedes V6 diesels, some BMW B57).
Can I drive with P0407?
Short-term yes. The ECU disables the affected EGR bank and falls back on the other bank, causing uneven idle and reduced power. Diesels may 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?
Usually no. P0407 on a 4-cylinder engine usually means the workshop manual labels the existing single sensor as 'B' due to manufacturer convention, or the engine has a primary plus secondary feedback (rare). On VW EA189/EA288, BMW N47/B47, and Mercedes OM651, the relevant code is normally P0405 not P0407.
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 a clogged DPF, NOx sensor faults, or AdBlue limp-mode countdown that result from continued EGR failure. On Audi 3.0 TDI V6 with dual EGR, budget for both sides to be inspected, since one failure often signals the other is close behind.
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