CEL Code 21 VTEC not working

[Glocker]

OK, so the past few weeks I had hot start problems. The car cranks but doesn't start unless I let it cool down for 5-10 minutes. When it does large amounts of black smoke came out. No CEL during this time. Then I did the main relay repair, checked the injectors (4th one had the plastic bit on the tip broken so I bought a set of refreshed injectors). After installing them I checked for the hot start problem; it's still there, and this CEL code 21 came on (found after using the pin and counting the flashes). I'm still getting hot start problems and now VTEC doesn't engage. Has new oil and new spark plugs (old ones all fouled from running so rich). Can anyone help?

[ECU-MAN]

Code 21 is due to the ECU not seeing the VTEC solenoid, either you left it disconected or you damaged the wire or solenoid when working on your car.

when the car does not start does the MIL (engine lamp) stay on and not go out ?

some possible reasons for the engine not starting when hot

- faulty ECU
- faulty ICM
- faulty ECT circuit
- faulty IAT circuit

it also helps to specify the type of car andengine you have.

this link may aslo help
http://www.ozhonda.com/forum/showthread.php?67113-DIY-PGMFI-Diagnostics-Codes

[Glocker]

Code 21 is due to the ECU not seeing the VTEC solenoid, either you left it disconected or you damaged the wire or solenoid when working on your car.

when the car does not start does the MIL (engine lamp) stay on and not go out ?

some possible reasons for the engine not starting when hot

- faulty ECU
- faulty ICM
- faulty ECT circuit
- faulty IAT circuit

it also helps to specify the type of car andengine you have.

this link may aslo help
http://www.ozhonda.com/forum/showthread.php?67113-DIY-PGMFI-Diagnostics-Codes

Thanks for the reply. My ECU is a P72 and I'm running a 95' B18C2. I've checked continuity on all the solenoid plugs and the ECU, and after I replugged the ECU back in the CEL code 21 went away. However CEL 6 came up, but then also went away after a hard reset. Currently there is no CEL light. I'm going to replace my ECT sensor and see if it solves the problem.

[ECU-MAN]

I suspect you turned on the ignition with some connectors disconnected when you worked on your injectors. If you clear the codes from the ECU and go for a drive where the engine reaches operating temp and the engine lamp does not come on then you should be OK.

[dorikin]

Thanks for the reply. My ECU is a P72 and I'm running a 95' B18C2. I've checked continuity on all the solenoid plugs and the ECU, and after I replugged the ECU back in the CEL code 21 went away. However CEL 6 came up, but then also went away after a hard reset. Currently there is no CEL light. I'm going to replace my ECT sensor and see if it solves the problem.

Good probability it's the ECT sensor. When faulty, the ECT sensor can tell the ECU to inject too much fuel during warm/hot start up causing flooding

[Glocker]

Hi guys, I've replaced my ECT sensor and the problem went away. It's fine now. Thanks for the help. For the record you can buy one from Mekong Spares for $40 with a years warranty. Ebay has them for $20ish shipped.

Tagged this thread for future references.

[mocchi]

fuark nice. good to know

[dougie_504]

Nice work. Pity I can't rep ECU-MAN more.