Loads of DTC's mk5 1.6 fsi please help

[davrosgolf]

Will start occasionally and idle at strange rpm's won't rev over 4000 ever and eml and epc lights are on.
Rev gauge seems to jump occasionally when ignition is on but engine not running?
Rev gauge seems to have spasms but the are related to engine rpm so i think the gauge triggering is ok but here are the list of codes vag com gives out:
18041 - Accelerator Position Sensor 2 (G185): Signal too Low
P1633 - 002 - Lower Limit Exceeded
17811 - EGR System: Regulation Deviation
P1403 - 008 - Implausible Signal
18321 - Pressure Sensor for Brake Boost (G294): Short to Ground
P1913 - 002 - Lower Limit Exceeded
17477 - NOx Sensor (G295) Heater Control: Short to Ground
P1069 - 002 - Lower Limit Exceeded
16706 - Engine Speed Sensor (G28): No Signal
P0322 - 004 - No Signal/Communication - Intermittent
18322 - Pressure Sensor for Brake Boost (G294): Implausible Signal
P1914 - 002 - Lower Limit Exceeded
19498 - Heater Regulation: Implausible Signal
P3042 - 002 - Lower Limit Exceeded - Intermittent
Readiness: 1110 0101
Any help would be greatly appreciated

[bartleaj]

If you have access to VCDS the first thing to check might be 01 Engine, 08 Measuring Blocks and specifically MB 62. The first 2 channels show the tellbacks from the throttle body G187/G188 and when you press the accelerator pedal (engine not running) one will go from approx 13% to 87% and the other will go from 87% to 13%. The last 2 channels show what the signals from the accelator pedal G79/G185 are and typically these will run from approx 14% to 80% and the other 7% to 40%. This will at least show if you have a fault with the potentiometers operated by the accelerator pedal or the throttle body itself. However I am puzzled by the number of seemingly unrelated faults which you have. Is it possible that moisture has got into the connectors to the engine ECU? It might also be an idea to re-post your message to the VCDS help page as there may be experts there who can help more than me.

[davrosgolf]

Right sorry for not posting again but we had this problem sort of fixed for a while by changing the crank sensor .
But now limp mode is back again and seems to generate a random assortment of codes.
When it first broke down we had a huge list of codes on of which being the egr system so i did the component tests off autodata and found it was fubared open circuit on the valve assembly so new valve was fitted which has solved the egr problems but not solved limp mode.
When it originally broke down on the motorway last time the aa man cleared the codes and wiggled the relays near the diagnostic port and it drove for another 30 miles.
This morning drove it 3 miles and the dash lit up again and limp will happen more often when car is cold.
This morning the codes were:
P1633 Accelerator Pedal low signal G185
P1913 Brake boost sensor low limit exceeded short to ground.
P1069 Nox Lower limit.
Two days ago there was no nox code but crank sensor code.
Due to the short to ground codes i think there is an earth fault.
Did the above test using vcds and found that sometimes the acc pedal does go out of spec but intermittantly. The last channel going from 5% up to 35% but sometimes dropping out to zero.
Could the short to ground faults all be a common wiring fault affecting the can bus system? Seems strange that the codes generated change with the weather but P1633 and 1913 are always present and were present in the original mega list of codes.