1997 Toyota Tacoma LX (3.4L V6, Automatic). In late 2020 the check engine light came on just before it was due for inspection. I ran my MaxiScan and received codes P0402 01/02 & P0202 P 02/02. I watched a few YouTube videos and believed the problem was the EGR Vacuum Modulator. I bought a Wells EVM33 EGR Vacuum Modulator and put it on. I cleared the codes and drove about 50 miles before inspection and thankfully it passed. About a month later the check engine light is back and throwing the same codes. Please help! Thx
What are the whole definitions of those codes?
Come to find out the problem was the vacuum switching valve. Changed it out and no more issues.
That’s for posting back with the fix.
Well, you might want to read these:
https://repairpal.com/obd-ii-code-p0202
https://repairpal.com/obd-ii-code-p0402
Excerpt - The code P0402 is often not a problem with the EGR valve itself. Rather, the EGR system is allowing excessive exhaust gases to flow back in to the combustion process or allowing them to flow when they should not, like when the vehicle is idling. Once the code P0402 has been retrieved with a scan tool, the freeze frame data should be documented and analyzed in order to determine what engine conditions were present when the code was triggered. It is recommended that the vehicle be driven in such a way as to duplicate the code setting conditions with a data streaming scan tool connected, so the behavior of the EGR actuating components and feedback sensors can be monitored. Pay close attention to the DPFE and/or EVP signal in the data stream.
