P2398 code meaning
Diesel Intake Air Flow B Position Sensor Circuit Low
Powertrain system Generic code P23xx codes Check engine light
What P2398 means
P2398 is logged when the position signal of the B intake throttle falls below its lower limit. Likely reasons are a signal lead shorted to ground, a lost 5 V supply, or a broken signal wire that the module input pulls low; on SENT sensors the transmitted raw value can also leave its range. No manufacturer documents P2398 itself. For the A valve, GM's LML reacts to less than 0.40 V persisting 5 s, its SENT-equipped 2017 diesels to under 1 % of 5 V in 200 of 250 checks (two trips), while Ford's 2023 diesels flag readings under 0.08 V lasting 3 s. If several 5 V sensors fail at once, suspect a shorted shared reference circuit. The flap is normally switched off, leaving the EGR loop with less control.
P2398 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 2 hours
- Clears after repairAfter a drive cycle
Symptoms of P2398
- MIL on
- Further 5 V sensor codes at the same time
- Regeneration suspended
Common causes of P2398
- Most likelySignal wire shorted to ground
- PossibleOpen 5 V reference or open signal wire
- PossibleShared 5 V reference pulled down by another faulty sensor
- Less likelyInternally failed position sensor
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Diesel intake throttle position sensorDiesel intake throttle valveSensor wiring
What each part of P2398 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 3 | Area: ignition system or misfire. |
| 98 | The exact fault in that area. |
What to do next
- Note P2398 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2398
What does P2398 mean?
P2398 means "Diesel Intake Air Flow B Position Sensor Circuit Low". P2398 is logged when the position signal of the B intake throttle falls below its lower limit. It is a generic code, so it means the same on every make.
Is it safe to drive with P2398?
Drive gently and only to a workshop. With P2398 the car can go into limp mode (reduced power) to protect itself.
Will P2398 fail an emissions test?
Yes, it can. P2398 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2398 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P2398 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.