P045B code meaning
EGR B Control Circuit Range/Performance
Powertrain system Generic code P04xx codes Check engine light
What P045B means
Exhaust gas recirculation (EGR) routes part of the exhaust back into the intake to lower combustion temperature and NOx. EGR B is a second EGR valve next to valve A – on diesels with two EGR circuits the low-pressure valve, which takes exhaust after the particulate filter and feeds it in before the turbo compressor. GM's diesels of 2016–18 and FCA's 2.2-litre diesel in the Jeep Wrangler use it. P045B means the drive circuit of valve B is electrically valid, but the feedback – current, voltage or position response – does not match the command. No manufacturer document available to us uses this code; the description follows the valve A counterpart P0404 and CARB, which requires output functions to be checked where feasible. Typical is a coked, stiff valve.
P045B at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P045B
- Check engine light on
- Low-pressure EGR switched off, possibly higher NOx
- Usually no change in driving
Common causes of P045B
- Most likelyValve B coked or stiff
- PossibleContact resistance in connector or wiring
- PossibleActuator motor worn internally
- Less likelyEngine module software or calibration
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
EGR valve bLow pressure EGR valveEGR wiringEngine control module
What each part of P045B means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| 5B | The exact fault in that area. |
What to do next
- Note P045B 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 P045B
What does P045B mean?
P045B means "EGR B Control Circuit Range/Performance". Exhaust gas recirculation (EGR) routes part of the exhaust back into the intake to lower combustion temperature and NOx. It is a generic code, so it means the same on every make.
Is it safe to drive with P045B?
Drive gently and only to a workshop. With P045B the car can go into limp mode (reduced power) to protect itself.
Will P045B fail an emissions test?
Yes, it can. P045B 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 P045B to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will P045B 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.