P045B: 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. 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.

Medium severity. Can I keep driving?You can normally drive in moderation, but get it repaired soon: if the valve is stuck open, the engine may idle very poorly.

Symptoms

Check engine light on
Low-pressure EGR switched off, possibly higher NOx
Usually no change in driving

Most likely causes

Valve B coked or stiff
Contact resistance in connector or wiring
Actuator motor worn internally
Engine module software or calibration

What to check, in order

Start with the simplest. You can tick off each step.

Check the connector and any vacuum hoses
Compare the reading with other engine data while varying the engine speed.
Use live data to compare the commanded opening with the actual opening
Clean the valve and passages if they are clogged with carbon
Test the actuator with the scanner
Replace the valve if it still does not follow the command after cleaning

Good to know

Repair difficulty: medium
It can trigger limp mode.
It affects emissions.

What each character of P045B means

P: Powertrain: engine and transmission
0: Generic code: same on every make
4: Emissions
5B: Specific fault in that system

Frequently asked questions

Can I keep driving with code P045B?

You can normally drive in moderation, but get it repaired soon: if the valve is stuck open, the engine may idle very poorly.

What causes code P045B?

The most common causes are: valve B coked or stiff; contact resistance in connector or wiring; actuator motor worn internally.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.