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2002 Jeep Grand Cherokee P0443 Code: How to Fix EVAP Purge Solenoid Circuit Issue

Model: 2002 Jeep Grand Cherokee Fault Code: P0443 Posted: 2015-11-03 14:37

I'm a hobby mechanic trying to get my 2002 Jeep Grand Cherokee back on the road. The vehicle is failing emissions tests due to a persistent check engine light and code P0443 — which indicates an issue with the EVAP purge solenoid circuit. I recently replaced the canister purge valve and reset the ECU by disconnecting the battery, but the warning light came back after only about 10 miles. The code reappeared during a second diagnostic scan. I'm wondering if there are any other troubleshooting steps besides replacing the ECM (or PCM), as that would cost around $200 — which seems excessive for this issue. I've already checked the fuses and replaced the gas cap, but I'm still unsure how to properly test voltage at the purge valve. Could someone clarify what exactly needs to be tested?

Related fault codes
P0443
Comments (8)
Anonymous 2015-11-03 15:55

P0443 refers to an EVAP purge solenoid circuit fault — not a problem with the ECM or PCM. DO NOT REPLACE ANY COMPONENT BASED ON CODE ALONE. Always verify basic electrical and mechanical components first. Key steps: - Check fuse #21 (10A) in the fuse box. - Verify 12V supply at the purge valve’s DB/WT wire (dark blue with white stripe). Please confirm these after your inspection — this will help determine the next troubleshooting step.

Anonymous 2015-11-07 12:27

I checked the fuses and found no blown ones. I replaced the gas cap as a precaution, but I don’t understand what '12V at purge valve DB/WT wire' means — could you explain this in simpler terms? I'm not very familiar with wiring diagrams or test procedures.

Anonymous 2015-11-07 14:02

At the purge valve connector, there are two wires. Disconnect the plug and use a test light or digital multimeter to check for 12V on the dark blue wire with white stripe (DB/WT). This is the power supply wire. Does your meter show voltage? If not, the issue may be in the wiring or fuse. Confirm this with a proper voltmeter — a simple test light might not give accurate readings.

Anonymous 2015-11-27 15:13

I thought I had a multimeter, but I can't find it right now. I'm heading to Harbor Freight to buy one. In the meantime, I was researching and found that a new PCM replacement costs about $200 — which is really expensive for this issue. Is there any chance a used or junkyard part could work? And would it need programming with my VIN?

Anonymous 2015-11-27 15:55

A $200 PCM seems low for a new unit — especially if you're considering a junkyard part. Even then, such parts must be flashed and programmed to your vehicle’s VIN. You’ll also need proper wiring harnesses (TPins) and a digital voltmeter to test voltage at both the purge solenoid and the PCM itself. Without these tools, testing is unreliable.

Anonymous 2015-11-27 19:13

Thanks for the info — I found a pre-coded PCM on fs1inc.com that matches my Jeep’s VIN. It's already programmed. Would this be a viable option? Or are there risks with using a used part?

Anonymous 2015-11-27 19:25

It’s highly unlikely the issue is with the PCM. A $200 price point seems low for a new unit, and even if you find a junkyard one, it would need proper programming and testing. The real fix likely lies in wiring or circuit continuity — start with voltage checks at the purge valve before considering any module replacement.

Anonymous 2015-11-28 17:03

After researching online forums, I discovered that someone had their purge solenoid installed upside down — which caused a persistent P0443 code. I double-checked my installation and found it was indeed mounted backward. This is why the check engine light has been on for years. After correcting the orientation and resetting the ECU, the light went off permanently. I’m now confident this was the root cause — no need to replace any modules or spend hundreds of dollars.