P2170
Exhaust Pressure Regulator Vent Solenoid Control Circuit Low
Auxiliary emissions control
Generic OBD-II
Medium
What it means
P2170 means the ECM detected low voltage on the control circuit for the exhaust pressure regulator vent solenoid — a valve used mainly on diesels to manage exhaust back-pressure for warm-up and emissions. Despite some databases labelling it a back-pressure sensor, this is a solenoid control-circuit fault, usually caused by wiring or the solenoid itself.
Medium
Can I keep driving? Usually safe to keep driving — it mainly affects engine warm-up and emissions — but slow warm-up, weak cabin heat, or reduced exhaust braking can result until it's repaired.
Common symptoms
What you'll notice
- Check-engine light on
- Slower engine warm-up in cold weather
- Reduced cabin heat (on affected diesels)
- Reduced exhaust-brake effect (where fitted)
Common causes
Most likely first
- Open or shorted wiring in the vent solenoid control circuitLikely
- Faulty exhaust pressure regulator vent solenoidCommon
- Poor or corroded connector at the solenoidCommon
- Faulty ECM driver for the solenoid (rare)Less often
How to diagnose & fix
Work through it in order
- Inspect the vent solenoid connector and control wiring for damage, shorts, or corrosion.
- Measure the solenoid's resistance and compare to spec.
- Check the control-circuit voltage from the ECM to the solenoid.
- Repair wiring faults or replace the solenoid if it's out of range.
- Clear and retest; verify the regulator operates.
FAQ
Quick answers
Is it safe to drive with P2170?+
Generally yes. This circuit controls exhaust back-pressure for warm-up and emissions, not core engine running, so you can usually drive while arranging a repair.
Can I just clear P2170?+
It comes back while the wiring or solenoid is faulty, and the regulator won't work correctly until it's fixed.
Related codes
Often seen with P2170
Read & clear P2170 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX