What it means
Same as P04A6 with the signal in plausible range but not matching the actual valve angle.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The position sensor on exhaust pressure control valve B reports the valve angle to the control module. P04A7 sets when the signal is electrically plausible but the reported position does not match the movement or position the module expects.
Common causes
Most likely first.
- Position sensor drift or failure
- Loose sensor mounting or linkage
- Damaged or corroded connector
- Fault in the valve or control circuit
Symptoms
- Check engine light on
- Reduced engine power or sluggish acceleration
- Engine may take longer to warm up or have reduced performance
- Exhaust braking may be reduced, if equipped
How to diagnose it
- Record freeze-frame data and compare commanded and reported positions for valve B to identify when their readings diverge.
- Inspect valve B's sensor mounting, linkage and connector for looseness, movement, corrosion or damage.
- Command valve B through its range with a scan tool and check whether sensor feedback follows smoothly and consistently.
- Check the sensor signal and wiring for intermittent changes while gently flexing the harness.
- If wiring and linkage are sound, verify sensor alignment and test the valve B sensor using the manufacturer's procedure.
Common fixes
- Secure loose valve B sensor mounting or linkage.
- Repair damaged or corroded wiring and connector terminals.
- Correct sensor alignment if the manufacturer's procedure identifies an offset.
- Replace a drifting position sensor or valve B assembly if testing confirms inaccurate feedback.
Can I keep driving?
If the vehicle runs normally, drive gently to arrange diagnosis; valve B control and exhaust braking may be reduced. Avoid heavy loads and steep descents if equipped, and stop if power loss becomes severe.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.